LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


GAGES  AND  GAGING  SYSTEMS 


Gages  and  Gaging  Systems 

DESIGN,  CONSTRUCTION  AND  USE  OF  TOOLS, 
METHODS    AND    PROCESSES    INVOLVED 

A  Treatise  and  Mechanics'   Reference  Work  upon   the   Funda- 
mentals, Principles,  and  Practices  of  Designing,  Constructing, 
Using  and  Adapting  Gages,  Precision  Instruments,  Indicators, 
Squares,  Verifying  Tools,  Test  Measurement  Instruments 
and  Micrometers  for  Use  in  the  Working  of  Metal  Parts 
and  the  Reducing  of  Surfaces  to  Accurate  Dimen- 
sions,  Including  Descriptions  of  the  Value,  Use 
and  Installation  of  Gaging  Systems,  Tools  for 
Manufacturing  Mechanism,  Testing  Methods 
and  Measurement  Systems  for   Insuring 
the  Production  of  Accurate  Duplicate 
Parts  and  Interchangeability  in  the 
Modern    Economic    Manufacture 
of  Precision  Machinery,  Tools, 
Punches,    Dies    and    Accu- 
rate  Repetition  Parts 
of  Metal 


By  JOSEPH  V.  WOODWORTH 

Author  of  "  Grinding  and  Lapping,  Tools,  Method's  and  Processes"  "  Dies,  Their  Construction 

and  Use,"    "  Hardening,  Tempering,  etc.,  of  Steel,"  "  American  Tool  Making  and 

Interchangeable  Manufacturing,"    "Punches,   Tools   and   Dies   for 

Manufacturing  in  Presses" 


1908 

HILL   PUBLISHING   COMPANY 

505   PEARL   STREET,  NEW   YORK 
6   BOUVERIE    STREET,  LONDON,  E.G. 

American  Machinist  —  Power  —  The  Engineering  and  Mining  Journal 


Copyright,  1908,  BY  THE  HILL  PUBLISHING  COMPANY 

N> 
<\\ 


ENTERED    AT    STATIONERS'    HALL 


Hill  Publishing  Company,  New  Tork,  U.S.A. 


PREFACE 

THIS  treatise  is  intended  as  a  reference  work  and  text-book 
for  all  practical  men  who  are  engaged  in  the  manufacture  of  pre- 
cision tools  and  interchangeable  parts.  It  is  hoped  that  all  having 
to  do  with  the  manufacture  of  interchangeable  work  will  find 
in  these  pages  a  comprehensive  treatise  on  the  design,  construc- 
tion, installation  and  use  of  the  most  modern  gages  and  gaging 
systems  that  have  been  evolved  in  our  best  American  shops. 

Throughout  the  entire  book  it  has  been  the  aim  to  eliminate 
all  obsolete  practices  and  methods;  and  to  confine  the  treatment 
exclusively  to  the  design,  construction,  use  and  adaptation  of  the 
numerous  tools  and  systems  illustrated.  It  has  further  been  the 
aim  to  make  these  descriptions  as  brief  and  concise  as  possible, 
and  always  of  the  most  up-to-date  and  approved  methods  of  con- 
struction, but  never  to  the  neglect  of  the  fundamental  principles 
involved. 

While  a  number  of  the  tools  taken  and  methods  described  are 
original,  the  majority  have  been  selected  from  the  columns  of 
the  American  Machinist  and  Machinery.  The  author,  therefore, 
begs  to  extend  his  thanks  to  the  publishers  of  these  journals  and 
also  to  the  writers  of  the  articles  collectively,  for  the  valuable 
data  and  information  which  have  made  this  compilation  possible. 

It  is  hoped  that  the  work  will  assist  the  present-day  mechanic 
*  in  the  design,  construction,  and  use  of  expedient  and  economical 
gages  and  gaging  systems,  and  that  it  will  also  be  the  means  of 
increasing  the  output  and  efficiency  of  duplicate  machinery,  and 
at  the  same  time  be  instrumental  in  lowering  the  cost  of  produc- 
tion on  interchangeable  work. 

JOSEPH  V.  WOODWORTH. 

BROOKLYN,  N.  Y. 
January,  1908 


CONTENTS 

SECTION    I 

GAGE  MAKING;  FUNDAMENTALS,  PRACTICE,  DEVELOPMENT  AND  EFFICIENCY 
OF  THE  TOOLS 

Gages  and  Gaging  Systems  —  Their  Use  —  Shops  in  which  Gaging 
Systems  are  Unknown  —  Interchangeability  and  Measurement  Instru- 
ments—-Gage  Making  —  Making  a  Taper  Plug  and  Ring  Gage  — 
Grinding  Out  Small  Ring  Gages  —  Grinding  and  Lapping  a  Male  Plug 
Gage  —  Preparation  of  Emery  for  Lapping  Gages  —  Lathe  Attachment 
for  Facilitating  the  Cutting  of  Thread  Gages  —  Measuring  Gages  when 
Threading  —  Points  in  Gage  Setting  —  Renewal  of  Thread  Gages  — 
Indicator  for  Thread  Gages  —  A  Thread-Testing  Gage  —  Making  and 
Using  Gages  for  Manufacturing  Mechanism  —  Ring  Gages  —  Com- 
bination Bench  Gage  —  Different  Forms  of  Pin  Gages  —  Variation  in 
Size  of  Work  Due  to  Type  of  Gage  —  Some  Gaging  and  Measuring 
Methods  at  the  Works  of  the  Westinghouse  Machine  Company  —  Limit 
Gage  Practice  at  the  Works  of  Ludw.  Loewe  &  Company  —  Use  of 
Gages  and  Indicators  in  Jig  and  Fixture  Work  —  Indicating  Gage  for 
Use  on  Milling  Machine  —  Vernier  Method  of  Locating  Work  on  Milling 
Machine  —  Boring  Master  Gage  Plates  from  Models  —  Making  Master 
Plates  for  Watches  —  Use  of  Gages  and  Indicators  in  Accurate  Index 
Plate  Making  —  Testing  Gage  for  Index  Plates  —  Making  Another 
Accurate  Index  Plate i~47 

SECTION   II 

ACCURATE  TEST  AND  INSPECTING  GAGES,  ELECTRIC  AND  OTHER  MEASUR- 
ING MACHINES;  TOGETHER  WITH  SPECIAL  INDICATORS  FOR  INSPECT- 
ING DUPLICATE  WORK 

Inspection  Gage  for  Wall  Thickness  —  Test  Gage  for  Width  of  Dove- 
tail Channels  —  Decimally  Graduated  Gage  for  Dovetail  Slide  Inspec- 
tion —  Decimally  Graduated  Slide  Gage  for  Dovetail  Inspection  — 
Large  Micrometer  Test  Caliper  for  Marine  Engine  Liners  — A  Test 
Gage  for  Large  Duplicate  Rollers  —  A  Set  of  Simple  Shop  Gages  — 
Gages  for  Locating  Keyseats  —  The  Testing  and  Comparison  of  End 
Standards  of  Length  —  Bar  Gages  with  Plain  Parallel  Ends  —  Cylin- 
drical Gages  —  Sphere  or  Bar  with  Spherical  Ends  —  Description  of 
Measuring  Machine  —  Materials  Used  in  Machines  —  Measuring 


viii  CONTENTS 

Bar  Gages  with  Flat  Ends  —  Measuring  Cylindrical  Gages  —  Sensitive 
Attachment  for  Measuring  Instruments  —  A  Device  for  Testing  Gages 

—  A  Testing  Tool  for  Fine  Work  —  A  Roll  Gage  —  A  New  English 
Type   of   Universal   Limit   Gage  —  A  Device   for  Testing   Squares  — 
Micrometer  Heads  for  Special  Gages 48-87 

SECTION   III 

LATHE,  PLANER,  SURFACE  AND  UNIVERSAL  GAGES  AND  INDICATORS;  THEIR 
CONSTRUCTION  AND  USE 

Simple  and  Inexpensive  Lathe  Indicators  —  A  Universal  Lathe 
Indicator  —  A  Decimally  Graduated  Universal  Indicator  —  A  Lathe 
and  Planer  Indicator  —  To  Adjust  the  Needle  of  a  Surface  Gage  —  A 
Tool-maker's  Scratch  Block  —  A  Cheap  Surface  Gage  —  A  Surface 
Gage  and  Indicator  —  Indicators  as  Applied  to  Milling  Machines  —  A 
Test  Indicator  —  A  Test  Indicator  and  Holder  —  Inclinometer  and 
Indicator  —  A  Lathe  Indicator  —  A  Test  Indicator  —  The  Use  of  Test 
Indicators  for  Testing  Work  —  The  R.  R.  Universal  Test  Indicator 
and  Hight  Gage  —  A  Scale  and  Vernier  for  Fine  Adjustment  of  the 
Milling  Machine  Table  —  Universal  Surface  Gage  with  Micrometer 
Adjustment  ....'. 88-112 

SECTION  IV 

THREAD,  WORM,  GEAR  TOOTH,  DEPTH  AND  MISCELLANEOUS  TEST  TOOLS; 
THEIR  CONSTRUCTION,  USE  AND  ADAPTATION 

A  Worm  and  Spiral  Gear  Tooth  Gage  —  Handy  Thread,  Worm  and 
Depth  Gage  —  German  Thread  Gages  —  A  Piston-Rod  Thread  Gage 

—  A  Taper  Gage  —  Micrometer  Depth  Gage  —  Making  an  Armature 
Segment  Templet  —  Making  a  Templet  —  Templets  for  Planing  a  Lathe 
Bed  —  A  Permanent  Snap  Gage  —  Set  of  Shop  Gages  —  Rod  Gaging 
Fixture  —  A  Planer  Gage  —  Gages   for  Textile  Machine  Work   .    113-140 

SECTION   V 

INSIDE  MICROMETER  CALIPERS  AND  OTHER  GAGES  FOR  INTERNAL  MEASUR- 
ING; THEIR  CONSTRUCTION  AND  USE 

Making  Small  Inside  Micrometer  Gages  —  An  Inside  Micrometer  — 
Inside  Micrometer  Calipers  —  Micrometer  Gage  — -  Inside  Gage  — 
Inside  Micrometer  for  Measurements  up  to  Four  Inches  —  Inside 
Micrometer  Caliper  ..V  .  .  •  •  U  '.  .  .  '  :  .  .  .  .  141-151 

SECTION   VI 

HIGHT  AND  VERNIER  GAGES  AND  ATTACHMENTS;  THEIR  CONSTRUCTION, 
VALUE  AND  USE 

Attachments  for  the  Vernier  and  Dial  Test  Indicator  —  Parallel 
Vernier  Gage  —  Hight  Gage  for  Testing  and  Laying  Out  Fine  Work 
—  A  6-Inch  Hight  Gage  152-160 


;  CONTENTS  ix 

SECTION   VII 

TRY-SQUARES,  KNIFE-EDGE  SQUARES,  COMBINATION  SQUARES,  STRAIGHT- 
EDGES, TEST  AND  SIZING  BLOCKS,  TOGETHER  WITH  METHODS  FOR 
THEIR  CONSTRUCTION,  TESTING,  USE  AND  ADAPTATION 

Squares  and  Squares  —  How  to  Produce  a  Correct  Square  —  Method 
of  Testing  and  Adjusting  Try-squares  —  Using  Test  Blocks  in  Place  of 
a  Square  —  Simple  Method  for  Testing  a  Flat  Square  —  How  to  Make 
a  Knife-edge  Square  —  Knife-edge  Square  with  Handle  —  A  Set  of 
Knife-edge  Tools  —  A  Knife-edge  Straight-edge  —  Use  of  the  Com- 
bination Square  —  Parallel  Motion  Straight-edge  —  Adjustable  Sizing 
Block  —  The  Making  of  a  Real  Square  —  A  Precision  Square  —  A 
Remarkable  Surface  Gage  —  A  Micrometer  Hight-gage  .  .  .  161-195 

SECTION   VIII 

OUTSIDE  MICROMETER  CALIPERS,  TOGETHER  WITH  THEIR  ATTACHMENTS 
FOR  SPECIAL  MEASURING  AND  GAGING 

Micrometer  for  Screw  Threads  —  Measuring  External  Screw  Threads 
with  the  Micrometer  —  An  Equating  Micrometer  —  6-inch  Beam  Micro- 
meter—  10  x  12  inch  Micrometer  Caliper  —  How  to  Make  a  Large 
Micrometer  —  Large  Micrometer  Calipers  at  the  British  Westinghouse 
Works  —  A  Shop  Set  of  Micrometer  Calipers  —  Practical  Shop  Use  of 
Micrometers  —  An  Outside  and  Inside  Micrometer  —  Micrometer  Scrib- 
ing Block  —  Micrometer  Scales  —  A  Micrometer  Gear  Tooth  Gage  — 
Micrometer  Attachment  for  the  Lathe  — Micrometer  Caliper  for  Measur- 
ing the  Radius  of  Spindle  Drills  and  Similar  Pieces  Impossible  to  Measure 
Directly  —  A  Micrometer  Stop  —  Testing  Machine  Tools  with  a  Mi- 
crometer Caliper  —  Testing  the  Accuracy  of  a  Lathe  without  Special 
Tools — Johansson  Gages 196-233 


GAGES   AND   GAGING  SYSTEMS 

SECTION    I 

GAGE    MAKING;    FUNDAMENTALS,   PRACTICE,   DEVEL- 
OPMENT AND   EFFICIENCY  OF  THE  TOOLS. 

GAGES  AND  GAGING  SYSTEMS  —  THEIR  USE 

WONDERFUL  indeed  has  been  the  progress  made  during  the 
past  fifteen  years  in  the  production  of  interchangeable  machine 
parts,  and  repetition  articles  of  cast,  machined,  punched  and 
stamped  metals.  Now  it  goes  without  saying  that  this  progress 
is  due  more  to,  and  has  been  directly  brought  about  through,  the 
introduction  of  gages  and  gaging  systems  for  verifying  measure- 
ments and  insuring  the  production  of  none  but  perfectly  inter- 
changeable parts;  or  at  least  for  the  guaranteeing  of  the  parts 
coming  within  an  allowable  limit  of  variation. 

In  the  development  of  gages  and  gaging  systems  we  may  trace 
a  line  of  mechanical  development,  efficiency  in  the  operation  of 
machinery  and  tools,  and  the  elimination  of  hand  labor  that  is 
simply  phenomenal.  It  may  therefore  be  stated  without  fear  of 
contradiction  that  the  perfection  of  the  modern  interchangeable 
manufacturing  system,  the  cheap  and  rapid  producing  of  accurate 
jigs,  tools,  dies,  and  fixtures  for  machining  and  producing  repe- 
tition parts,  could  never  have  been  attained  but  for  the  develop- 
ment and  introduction  of  the  numberless  varieties  of  testing  and 
gaging  instruments  which  have  to-day  been  adopted  in  the  most 
progressive  shops  where  accurate  duplicate  work  is  produced. 

In  this  and  the  sections  which  follow,  it  is  our  object  to  illus- 
trate and  describe  the  design,  construction,  use  and  application 
of  gages  and  measuring  instruments,  which  may  be  adopted  to 
advantage  in  numberless  machine  shops  and  manufacturing 
establishments  throughout  the  world,  to  there  supersede  hand 
labor  in  the  production  of  metal  parts  and  to  also  insure  the 
verification  of  their  interchangeability. 


2  GAGES  AND  GAGING  SYSTEMS 

While  the  use  of  gages  has  progressed  wonderfully  in  the 
larger  manufacturing  establishments  and  is  becoming  more 
generally  understood  and  appreciated  every  day  in  the  smaller 
ones,  there  are  nevertheless  many  others  wherein  their  proper 
design  and  construction,  together  with  their  value  and  applica- 
tion, are  not  understood.  In  such  shops  where  these  error  de- 
tectors are  not  used,  tools,  parts  of  machines  and  small  articles 
of  metal  are  being  laboriously  brought  down  to  interchangeability 
by  hand  work,  and  then  tested  for  accuracy  by  tedious  and  un- 
reliable methods;  and  the  same  labor  could  be  accomplished  in 
one  fourth  the  time  by  means  of  suitable  gages  of  inexpensive 
construction  placed  in  the  hands  of  workmen,  who  should  be 
taught  how  to  use  them  properly. 

Aside  from  the  reduced  cost  of  producing  machine  parts  and 
articles  of  metal,  which  invariably  results  through  the  introduc- 
tion of  a  proper  gaging  system,  the  increased  efficiency  of  the 
articles  produced  is  a  factor  that  has  to  be  considered. 

Manufacturers,  managers  and  superintendents  of  machine 
building  and  metal  working  plants  should  realize  once  and  for 
all,  that  unless  they  install  an  up-to-date  gaging  system  and  place 
properly  constructed  gages  in  the  hands  of  their  operators,  the 
production  of  parts  that  will  interchange  at  any  and  all  times  and 
places  is  impossible. 

SHOPS  IN  WHICH  GAGING  SYSTEMS  ARE  UNKNOWN 

We  have  inspected  a  great  number  of  establishments  all  over 
the  United  States,  and  we  have  been  employed  in  them  also;  from 
the  small  back-loft  jobbing  shop  to  the  great  machine  works;  and 
we  have  come  across  a  wonderfully  large  number  wherein  the 
proper  use  of  gages  and  gaging  systems  was  unknown  and  unheard 
of.  Therefore,  we  state  that  if  any  superintendent  of  a  shop 
wherein  the  use  of  modern  gages  has  been  ignored  will  make  a  trip 
of  inspection  through  the  departments  of  the  works  which  he 
directs,  he  will  not  have  proceeded  far  before  becoming  possessed 
of  a  painful  realization  that  his  concern  is  paying  for  a  lot  of  unpro- 
ductive labor.  If  he  is  at  all  progressive  he  will  then  give  up  some 
of  his  time  to  the  study  of  gaging  systems,  to  a  gaining  of  a  proper 
knowledge  of  the  use  of  gages,  and,  afterwards,  to  the  introduc- 
tion of  a  proper  system  of  gaging  in  his  departments.  More  and 


GAGES  AND  GAGING  SYSTEMS  3 

better  work  will  be  the  result  of  this  innovation,  because  inter- 
changeability  and  efficiency  of  the  articles  and  parts  will  be 
guaranteed  before  they  leave  the  hands  of  the  machine  operators. 
There  will  then  be  no  chance  for  inaccurate  work  leaving  the 
shop;  there  will  then  be  no  opportunity  for  the  assembling  of 
inaccurate  parts  into  machines  or  tools.  Lastly,  economy  will 
result  through  the  cutting  out  of  operations  formerly  requiring 
skilled  help  to  perform,  and  through  the  elimination  of  much 
hand  labor.  The  operator's  skill  will  become  an  ineffective 
factor,  except  with  regard  to  the  quantity  of  the  output,  because 
the  use  of  gaging  tools  will  insure  the  production  of  perfect 
parts. 

INTERCHANGEABILITY  AND  MEASUREMENT  INSTRUMENTS 

From  a  mechanical  point  of  view  it  may  well  be  said  that  we 
are  living  in  an  age  of  interchangeability  brought  about  through 
the  use  of  and  perfection  of  instruments  for  measurement  and 
detection  of  error.  Never  before  have  mechanics  and  manu- 
facturers, and  in  general  has  the  world  of  industry,  made  use  of 
gages  and  gaging  systems  as  it  is  doing  now.  And  there  is  small 
wonder  for  this  state  of  affairs,  for  these  useful  tools  in  all  their 
different  phases  have  proven  to  the  satisfaction  of  the  greatest 
mechanical  economists  of  to-day  that  they  are  instruments  that 
work  for  the  reduction  of  cost  of  production,  the  perfect  efficiency 
of  products,  and  the  education  of,  and  increasing  the  skill  of,  the 
productive  workers. 

Of  course,  to  those  who  are  unfamiliar  with  the  gage  and  its 
modern  application,  the  statements  contained  in  the  foregoing 
may  appear  extravagant;  but  one  has  only  to  inspect  a  modernly 
equipped  and  perfectly  operated  manufacturing  plant  wherein 
accurate  machinery  is  built  in  large  quantities,  to  become  con- 
vinced of  the  surprising  rapidity  with  which  the  machine  tools 
in  use  therein  turn  out  accurate  work  in  a  steady  stream,  —  with 
the  operators  simply  occasionally  testing  a  piece  with  their  measur- 
ing instruments,  —  through  the  use  of  gages  and  the  proper 
installation  of  gaging  systems. 

Of  the  many  different  kinds  of  gages,  the  ancient  snap  and 
plug  gages  are  the  most  widely  known  and  used.  The  reason  for 
this,  we  might  say,  universal  use  of  these  two  types  is,  that  almost 


4  GAGES  AND  GAGING  SYSTEMS 

all  work  that  requires  the  use  of  various  other  kinds  of  measuring 
instruments  requires  the  use  of  one  of  these  two  first. 

GAGE  MAKING 

In  gage  making,  as  in  the  construction  of  all  verifying  instru- 
ments, the  fundamental  quality  that  works  for  success,  and  upon 
which  all  subsequent  results  depend,  is  accuracy.  This  the 
mechanic  must  always  keep  in  mind  from  the  very  moment  he 
cuts  off  the  stock  until  he  has  concluded  the  finish  lapping.  If 
any  error  does  creep  in  during  the  construction  of  a  gage  it  will, 
in  all  probability,  mean  a  great  deal  of  spoiled  work  if  it  is  allowed 
to  get  by  unheeded,  and  all  subsequent  care  in  performing  the 
remaining  operations  toward  completion  of  the  tool  will  not  avail 
in  eradicating  the  error.  Of  course,  if  the  error  is  such  that  upon 
investigation  it  is  ascertained  that  it  will  not  affect  seriously  the 
interchangeability  or  limit  of  variation  allowable  in  the  parts 
upon  which  the  gage  is  to  be  used  for  measurement  verifying, 
then  the  case  is  different,  as  the  defect  will  have  no  effect  in 
preventing  the  attainment  of  what  the  tool  is  required  to  in- 
dicate. 

MAKING  A  TAPER  PLUG  AND  RING  GAGE 

In  order  to  lay  before  the  reader  the  methods  of  gage  making, 
it  will  be  well  to  take  up  and  explain  in  detail  first  the  making  of 
a  small  taper  plug  and  ring  gage,  as  in  the  construction  of  tools 
of  this  type,  accuracy,  skill,  patience,  and  workmanship  of  the 
highest  order  are  absolutely  necessary. 

Of  the  steel  question  we  will  simply  state  that  no  grade  of 
steel,  however  good,  is  too  good  for  gage  work;  therefore  secure  the 
very  best  grade  of  steel  in  the  market.  The  expenditure  of  a  few 
cents  per  pound  over  the  usual  price  should  not  deter  one  from 
procuring  the  very  best,  when  it  is  considered  that  the  cost  of 
material  however  great  is  not  to  be  compared  with  the  cost  of 
labor  that  will  be  necessary  to  finish  the  tool.  Besides,  a  very 
small  defect  in  the  raw  material  will  often  not  make  itself  evident 
until  much  expensive  work  has  been  done;  then,  as  the  tool  is  of 
no  use,  the  loss  is  great,  A  steel  that  can  be  depended  upon  in 
annealing,  hardening  and  tempering;  a  steel  that  will  not  shrink 
or  warp  excessively;  a  steel  that  when  hardened  will  have  the 
minimum  of  spring  in  .it;  that  is  the  steel  to  use  for  gage  work. 


GAGES  AND  GAGING  SYSTEMS  5 

The  fact  is  well  known  that  it  is  extremely  difficult  to  pro- 
duce a  perfect  taper  plug  and  ring  gage  of  special  size.  Of  course, 
in  standard  sizes  of  these  gages,  they  may  be  had  of  manufac- 
turers with  their  accuracy  and  efficiency  guaranteed,  because  these 
people  make  a  specialty  of  manufacturing  lines  of  such  tools, 
and  their  workshops  are  fully  and  splendidly  equipped  for  turning 
out  such  tools  in  quantities. 

In  the  making  of  a  special  size  of  taper  plug  and  ring  gage, 
it  is  quite  impossible  to  secure  a  perfect  fit  by  simply  lapping  the 
tool  in  the  ordinary  manner  after  hardening.  This  is  so  because 
the  diameter  is  so  small  that  it  is  usually  quite  impossible  to  use 
a  wheel  to  grind  it;  therefore  it  becomes  necessary  to  use  the 
diamond  charged  lap  to  finish  it.  This  lap  is  not  used  in  the  same 
manner  that  the  ordinary  lap  is  worked:  instead,  it  is  used  in  a 
manner  similar  to  the  use  of  a  wheel  for  internal  grinding,  the 
diamond-charged  lap  being  placed  in  a  traverse  grinder  or  a  bench 
lathe,  and  with  the  female  gage  held  in  the  chuck  of  the  lathe, 
it  may  be  ground  easily  and  accurately,  care  being  taken  not  to 
crowd  the  cutting  qualities  of  the  lap.  The  result  of  forcing  the 
cutting  of  a  diamond-charged  lap  of  this  kind  is  a  finished  gage 
that  is  "bell-mouthed." 

When  using  the  diamond-charged  lap  for  work  of  the  kind 
above  indicated,  it  will  always  be  found  best  to  keep  the  lap  well 
lubricated  with  kerosene  oil.  Lubricated  in  this  manner  the 
lap  will  be  found  to  cut  much  more  freely  than  if  used  dry.  The 
results  will  also  be  much  more  satisfactory. 

The  diamond  powder  used  in  charging  laps  for  grinding  gages 
may  be  had  in  different  grades,  each  grade  being  known  by  a 
number.  On  fine  grinding,  No.  5  will  be  the  best  to  use.  On 
ring  gage  work,  however,  the  grade  known  as  "ungraded" 
answers  all  purposes  in  a  most  satisfactory  manner. 

GRINDING  OUT  SMALL  RING  GAGES 

When  grinding  out  very  small  ring  gages,  necessitating  the 
use  of  extremely  small  laps,  it  is  quite  difficult  to  ascertain  if  the 
lap  is  doing  any  cutting  as  the  work  revolves.  In  order  not  to 
take  advantage  of  this  to  crowd  the  lap  unknowingly,  a  little 
tool  known  as  a  "transmitter"  comes  in  handy.  This  "trans- 
mitter" can  be  quickly  and  easily  made  of  a  piece  of,  say,  No.  29 


6  GAGES  AND  GAGING   SYSTEMS 

drill  rod,  one  end  being  split  for  about  half  an  inch  up,  and  its 
two  parts  spread  so  that  they  will  straddle  the  spindle  of  the 
traverse  grinder.  On  the  other  end  of  the  rod  fasten  a  piece  of 
wood  shaped  in  a  neat  and  comfortable  manner  so  that  it  will 
rest  against  the  ear  of  the  workman.  This  arrangement  will  act 
as  a  telephone,  and  indicate  to  the  operator  when  the  lap  is 
removing  material  inside  the  gage. 

After  a  taper  ring  gage  has  been  made,  it  will  be  well  to  make 
a  perfect  lap  of  the  right  taper  and  lap  just  sufficient  to  remove 
the  marks  left  by  grinding,  which  are  usually  very  slight. 

GRINDING  AND  LAPPING  A  MALE  PLUG  GAGE 

The  male  or  plug  taper  gage  is  more  easily  made  and  finished 
than  the  female.  It  can  be  more  easily  handled  and  can  be  readily 
ground  in  a  universal  grinder.  It  can  then  be  lapped  with  a 
piece  of  babbitt  that  has  been  finished  off  perfectly  straight,  and 
the  finished  surface  charged  with  emery. 

In  the  making  of  sets  of  these  gages  the  plug  gage  is  usually 
made  first.  This  is  done  so  as  to  be  able  to  use  it  as  a  reference 
gage  when  grinding  out  the  female  gage.  However,  when  the 
mechanic  is  supplied  with  a  model  to  which  to  make  the  tools, 
then  the  female  gage  is  made  first  and  the  plug  afterwards  fitted 
to  it. 

PREPARATION  OF  EMERY  FOR  LAPPING  GAGES 

An  essential  necessary  to  the  workman  who  desires  to  become 
a  first-class  gage-maker  is  a  thorough  knowledge  of  the  proper 
preparation  of  the  emery  for  lapping.  It  should  be  prepared  in 
the  following  manner: 

Take  a  quantity  of  flour  emery  —  say  about  five  tablespoon- 
fuls  —  and  mix  it  with  a  cup  of  good  lard  oil.  Thoroughly  mix 
the  two  materials  together  and  allow  the  mixture  to  stand  over 
night.  In  the  morning  pour  the  mixture  off  into  another  cup, 
and  take  extreme  care  not  to  disturb  the  settlings,  as  these  set- 
tlings are  composed  of  large  grains  of  emery  and  should  be  thrown 
away.  Repeat  this  pouring  operation  three  or  four  times,  and 
the  result  will  be  a  mixture  that  will  produce  an  elegant  finish 
on  the  surfaces  of  both  male  and  female  gages. 


GAGES   AND   GAGING   SYSTEMS 


LATHE  ATTACHMENT  FOR  FACILITATING  THE  CUTTING  OF  THREAD 

GAGES 

When  the  last  cuts  are  taken  on  the  thread,  it  must  be  within 
one  ten-thousandth  of  an  inch.  For  this  reason  a  large  disk, 
shown  at  a,  Fig.  i,  is  of  service.  It  should  be  as  large  as  the 
lathe  will  permit;  in  this  case  it  is  4!  inches  in  diameter  and  |  inch 
wide  on  the  face.  It  is  turned  out  -j8g  inch  from  each  side  to 
make  it  light  and  neat  in  appearance.  The  disk  is  fastened  to 
the  cross-feed  screw  with  a  knurled  screw,  and  is  graduated  in 


n 


FIG.  i.  —  Thread  Cutting  Attachment. 

250  divisions,  and  stamped  on  each  side  of  the  zero  line  from  o  to 
125.  Arm  b  is  made  the  same  radius  as  the  top  of  the  disk,  and 
fits  the  hub  of  the  cross-feed  bearing.  It  is  split  at  the  end  and 
clamped  stationary  with  a  machine  screw.  The  graduations  on 
top  are  ten  in  number,  and  occupy  the  same  space  as  nine  divi- 
sions on  the  disk,  and  for  convenience  in  reading  are  stamped 
o,  1,2,  3,  4,  5,  6,  7,  8,  9,  o.  Accordingly,  when  a  line  on  the  disk 
coincides  with  the  first  line  of  the  vernier,  the  next  two  lines  to 
the  right  differ  from  each  other  one  tenth  of  the  length  of  a  divi- 
sion on  the  disk,  the  next  lines  differ  by  two  tenths,  etc.  This 
design  gives  the  thread  chaser  a  positive  position  when  feeding 


8  GAGES  AND  GAGING  SYSTEMS 

in  for  a  finishing  cut,  while  with  the  ordinary  micrometer  dial  to 
feed  in  less  than  one  thousandth  of  an  inch  is  a  case  of  guess  work, 
and  the  consequences  very  likely  are  that  the  tool  feeds  in  too 
far,  the  chaser  begins  to  tear,  and  the  thread  gets  rough  and 
loses  the  correct  shape  and  lead.  The  chaser  should  be  filed  on 
both  sides  the  same  angle  as  the  thread,  so  it  will  start  and  end 
with  a  full  thread,  and  not  more  than  three  threads  should  remain 
on  the  chaser;  then  it  should  be  hardened  in  an  open  fire  and 
drawn  to  a  light  straw. 

Another  good  attachment  for  thread  gage  cutting  is  the  sta- 
tionary tool-post  c,  Fig.  i,  which  takes  the  ordinary  style  of 
chaser.  The  post  is  fitted  rather  freely  to  the  T-slot  in  the  tool- 
block  and  clamped  with  two  machine  screws  and  two  nuts  d. 
A  set-screw  at  the  top  and  another  at  the  side  clamp  the  chaser, 
and  after  the  tool-post  has  been  once  located  and  set  square,  the 
chaser  will  always  be  located  properly  after  grinding.  Where  a 
tool-holder  is  used  with  a  removable  threading  tool,  this  tool-post 
is  not  required,  as  the  chaser  point  will  drop  squarely  into  its 
seat  after  grinding. 

MEASURING  GAGES  WHEN  THREADING 

A  good  method  for  measuring  the  thread  when  finished  is  to 
measure  in  the  thread  angle  by  using  an  ordinary  micrometer 
and  wires  of  different  diameters.  To  measure  large  threads, 
procure  an  ordinary  micrometer  head  from  any  of  the  manu- 
facturers of  measuring  instruments,  making  a  C-shaped  frame 
like  an  ordinary  micrometer  body,  except  that  the  anvil  should 
be  ii  inches  in  diameter,  and  the  frame  flat  on  the  bottom 
so  it  will  stand  upright;  bore  a  hole  in  the  top  of  the  frame 
to  fit  the  micrometer  head,  and  at  the  same  setting  turn  off 
the  face  of  the  anvil.  Great  care  should  be  taken,  after  harden- 
ing the  anvil  in  grinding  and  lapping,  that  it  is  perfectly  square 
with  the  micrometer  stem. 

POINTS  IN  GAGE  SETTING 

When  cutting  a  screw  plug  gage  it  should  be  roughed  out  with 
a  single-thread  tool,  within  .002  inch,  and  then  merely  finished 
with  a  chaser  so  as  to  prolong  the  life  of  the  chaser.  It  has  been 
found  when  chasing  that  the  lead  of  the  lathe  is  not  in  all  cases 


GAGES  AND  GAGING  SYSTEMS  9 

exactly  the  same  with  each  cut.  To  make  sure  that  the  lead  is 
perfect  when  the  last  cut  is  taken,  go  over  the  work  three  times 
with  the  chaser  in  exactly  the  same  position,  and  by  using  a  mag- 
nifying glass  see  whether  the  tool  cuts  any  at  either  side  of  the 
thread;  if  not,  then  the  lead  is  all  right.  The  chaser  should  never 
be  fed  in  more  than  .0003  inch  with  the  first  cuts,  and  .0001  inch 
with  the  last  two  cuts,  to  assure  a  smooth  thread,  and  it  is  ad- 
visable when  cutting  to  keep  the  screw  well  lubricated  with  lard 
oil,  and  for  this  purpose  a  square  tin  box  and  finger  brush  for  the 
oil  may  be  kept  under  the  chaser. 

A  ring  thread  gage  is  made  in  a  similar  manner,  but  it  is  never 
finished  with  an  inside  chaser,  except  where  such  is  required, 
where  taps  are  not  at  hand,  After  being  roughed  out  with  the 
chaser  it  is  finished  with  two  or  three  taps  with  a  difference  of 
two  thousandths  in  diameter.  On  smaller  ring  gages  inside 
chasers  cannot  be  used,  but  a  set  of  taps,  six  in  number,  are  used, 
these  varying  in  diameter,  one  from  another,  by  from  two  to  five 
thousandths  of  an  inch. 

RENEWAL  OF  THREAD  GAGES 

An  item  which  we  think  will  be  of  interest  is  the  renewal  of 
thread  gages,  with  which  no  doubt  we  have  all  had  the  same 
difficulty.  Three  plug  and  ring  gages  are  made  at  the  start,  all 
on  the  same  lathe,  and  hence  all  alike.  The  trouble  begins  when 
the  foreman  brings  the  manufacturing  or  the  inspector's  gage 
with  instructions  to  renew  the  plug,  as  the  old  one  is  worn  below 
the  standard  size.  The  old  plugs  were  made  some  time  ago. 
Perhaps  you  were  not  around  when  they  were  made  and  do  not 
know  what  lathe  was  used,  or  the  plugs  may  have  been  made  by 
an  outside  firm.  As  the  pitches  of  lead  screws  on  different  lathes 
are  seldom  alike,  it  is  necessary  to  find  a  lathe  to  cut  the  thread 
nearest  to  the  master  plug.  Should  a  lathe  be  used  that  has  an 
error  in  its  screw  of  a  couple  of  thousandths  in  the  length  of  the 
thread  on  your  master  plug,  trouble  will  follow.  Making  the 
new  plug  with  .002  for  lapping,  then  hardening  it  and  lapping  it 
to  accurate  size,  it  will  start  in  the  master  ring  gage  a  perfect  fit, 
but  on  screwing  it  in  a  few  threads  it  becomes  tighter,  and  by  the 
time  it  is  half  to  three  quarters  through  the  ring  gage,  it  fetches 
up  solid.  You  take  it  out  and  caliper  it,  thinking  you  may  have 


10 


GAGES  AND  GAGING  SYSTEMS 


lapped  it  a  little  taper,  but  finding  the  plug  perfectly  parallel, 
you  may  suspect  that  the  master  ring  is  a  little  bell-mouthed  on 
one  side  and  try  the  plug  in  the  opposite  side  of  the  ring  gage,  only 
to  find  it  acts  in  the  same  way.  What  is  the  trouble?  Nothing 
but  a  slight  error  between  the  two  leads.  Should  an  attempt 
be  made  to  lap  it  enough  to  bring  the  lead  on  the  plug  the  same 
as  on  the  master,  the  result  would  be  a  very  poor  fit  when  only 
a  few  threads  are  entered  in  the  ring  gage. 

INDICATOR  FOR  THREAD  GAGES 

We  find  we  cannot  make  a  good  job  of  a  plug  and  ring  if  the 
variation  in  the  two  leads  is  more  than  .0003  in  the  length  of  the 


FIG.  2.  —  Indicator  for  Thread  Gages. 


thread  on  the  plugs.  To  overcome  this  difficulty,  we  made  a 
little  tool,  or  indicator,  shown  in  Fig.  2,  for  comparing  the  lead 
of  any  lathe  screw  with  that  of  the  master  thread  plug.  Putting 
a  dog  on  the  master  plug,  placing  it  in  the  lathe  and  holding  the 
indicator  in  the  tool-post,  with  the  lathe  geared  to  the  proper 
pitch,  we  place  the  indicator  against  the  side  of  the  thread  on  the 
master  plug  hard  enough  to  bring  the  pointer  to  the  zero  mark, 
and  then  start  the  lathe  very  slowly  in  order  to  watch  the  pointer. 
If  it  remains  throughout  the  whole  length  of  the  master  plug  at 
zero,  one  may  be  sure  that  he  will  be  able  to  make  a  plug  on  that 
lathe  that  will  not  fetch  up  tight  when  half  way  through  the 
ring  gage. 

The  proportions  of  this  indicator  are  such  that  it  multiplies 
100  to  i ;  thus,  .001  of  an  inch  in  a  thread  will  show  .100  of  an 


GAGES  AND  GAGING  SYSTEMS  n 

inch  on  the  graduated  plate.  A  zero  mark  is  placed  at  each  end 
of  the  plate,  the  graduations  reading  each  way  and  marked  i,  2, 
3,  etc.,  thus  reading,  .001,  .002,  etc.  The  levers  swing  on  pivots 
with  6o-degree  points,  which  are  adjusted  by  fine  small,  fine- 
thread  screws,  acting  as  the  lower  bearings  of  the  pivoted  levers. 
A  small  coil  spring  encircles  the  rear  pivot,  and  bears  against  the 
last  lever  to  maintain  proper  pressure.  When  the  indicator  is 
brought  against  the  thread,  it  wants  to  bear  hard  enough  to  make 
the  last  lever  stand  at  zero. 

This  indicator  is  also  a  very  useful  tool  for  finding  if  a  lathe 
will  cut  a  micrometer  screw.  Take  the  screw  out  of  a  micrometer 
which  is  known  to  be  right,  and  remove  the  barrel  from  the  screw. 
Chuck  a  piece  of  steel  or  brass  in  the  lathe  to  be  tested,  and  bore 
the  end  to  fit  the  measuring  end  of  the  micrometer  screw  with 
the  thread  projecting.  Gear  the  lathe  to  40  pitch  and  apply  the 
indicator,  and  you  will  soon  know  if  a  micrometer  screw  can  be 
cut  on  that  lathe. 

It  is  often  good  policy  when  making  thread  plugs  and  rings, 
to  rough  them  out  without  cutting  the  threads,  and  harden  them 
as  if  they  were  finished,  and  then  anneal  and  cut  the  threads. 
This  process  no  doubt  does  away  with  a  lot  of  expansion  and 
contraction  of  the  steel  in  the  second  hardening.  Some  like  this 
method,  others  do  not.  We  have  had  very  good  success  with  it. 

A  THREAD-TESTING  GAGE 

A  very  efficient  thread-testing  gage  has  recently  been  patented 
by  the  Dresdner  Bohrmaschinen  fabrik  A.  G.,  formerly  Bern- 
hard  Fischer  &  Winsch,  of  Dresden,  Germany.  The  handling  of 
this  new  device,  as  shown  in  Fig.  3,  is  simple  and  easily  learned. 
Screws  can  be  tested  by  it  not  only  to  any  degree  of  accuracy, 
but  the  external  diameter,  diameter  at  a  root  of  thread,  pitch, 
and  form  of  thread  may  also  be  ascertained. 

The  testing  gage,  Fig.  4,  comprises  two  hardened  and  ground 
members  parallel  to  one  another,  solidly  connected  by  croLS- 
pieces  having  large  contact  surfaces  and  screws.  In  one  of  the 
members  A,  the  shape  and  depth  of  the  thread  has  been  accurately 
worked,  while  the  adjoining  surface  B  corresponds  to  the  external 
diameter.  On  the  opposite  ends  of  the  gage,  both  legs  are  smooth, 
spaced  apart  the  minimum  width  admissible  for  the  external 


12 


GAGES  AND  GAGING   SYSTEMS 


diameter  of  the  screw.     These  sizes  are  indicated  on  the  gage 
for  each  size. 

The  gage  is  used  as  follows:  One  first  tries  to  introduce  the 
screw  between  the  two  smooth  terminal  surfaces  C  of  the  legs; 
if  it  enters  the  external  diameter  is  too  small,  so  that  the  screw 
being  unavailable  need  not  further  be  tested.  If,  however,  the 
screw  does  not  enter,  the  test  is  continued  on  the  opposite  end. 
The  screw  should  readily  fit  into  the  gage  A,  Fig.  4.  On  entering 
the  point  of  the  screw,  it  is  ascertained  whether  the  pitch  and 
shape  of  the  thread  are  correct.  If  the  screw  can  be  introduced 
at  B  from  the  side  and  does  not  fit  in  A  from  the  front,  its  external 


FIG.  3.  — Thread -Testing  Gage. 

diameter  is  correct,  but  the  pitch  is  not.  Screws  having  the 
threads  that  are  not  stretched  or  otherwise  deformed  do  not 
pass  through  A. 

MAKING  AND  USING  GAGES   FOR  MANUFACTURING  MECHANISMS 

To-day,  when  a  piece  of  mechanism  or  a  machine  is  perfected 
and  ready  for  manufacturing,  the  first  thing  to  be  considered  is 
the  making  of  the  gages,  which  is  oftentimes  a  very  expensive  item, 
especially  when  the  mechanism  is  of  an  intricate  nature.  To 
obviate  errors  in  the  gage  making  is  a  very  essential  point  in  this 
class  of  work,  as  an  error  in  one  gage  may  affect  the  accuracy  of 
others,  or,  in  other  words,  this  inaccurate  gage  may  be  used  as  a 


GAGES  AND  GAGING   SYSTEMS  13 

master  to  make  others  too,  they  in  their  turn  being  used  on  different 
parts  of  the  mechanism.  Thus  the  error  may  be  multiplied  a 
number  of  times  before  being  detected,  and  when  at  last  found  it 
is  oftentimes  a  difficult  matter  to  correct  it,  as  it  may  be  that 
that  same  error  has  by  that  time  established  a  size  of  its  own  to 
which  many  other  gages  have  been  made,  and  to  rectify  it  may 
mean  the  overthrowing  of  all  the  gages  that  have  followed  the 
making  of  the  first  incorrect  one.  So  it  is  obvious  that  the  great- 
est foresight  and  skill  must  be  exercised  when  making  the  masters. 
It  happens  many  times  that  a  man  is  given  a  gage  to  make,  with 
orders  to  get  it  as  nearly  correct  as  he  possibly  can.  The  tool 


FIG.  4.  —  Thread-Testing  Gage. 

may  be  nothing  more  than  a  distance  gage  for  locating  one  hole 
from  another,  and,  moreover,  it  may  be  that  the  second  hole  is 
only  a  screw  or  clearance  hole.  The  tool-maker  criticises  the 
foreman's  orders  for  requiring  unnecessary  exactness,  but  the 
foreman  knows  why  he  gave  those  orders.  He  sees,  perhaps, 
that  he  must  use  that  second  hole  as  a  gaging  point  to  locate 
another  or  third  point  from,  as  the  gaging  of  this  from  the  first 
hole  would  require  an  unpractical  gage;  or  there  may  be  some 
obstruction  in  the  way  so  that  he  cannot  avoid  measuring  from 
the  second  hole.  We  do  not  advocate,  nor  is  it  advisable  to  use 
more  than  one  point  on  a  job  to  gage  from,  but  oftentimes  it 
cannot  be  avoided. 


GAGES   AND   GAGING   SYSTEMS 


RING  GAGES 

We  wish  to  mention  right  here  a  point  which  has  often  been 
brought  to  our  notice,  and  which,  while  having  nothing  to  do  with 
the  accuracy,  does  concern  the  construction  of  all  classes  of  limit 
gages.  Take,  for  instance,  the  ring  gage  shown  in  Figs.  5  and  6, 
having  two  hardened  and  lapped  bushings,  one  in  each  end  of  the 
large  knurled  ring  which  acts  as  a  holder;  there  is  a  difference  of 
.001  inch  in  the  inside  diameter  of  these  rings,  or  .0005  inch  limit 
each  way  from  standard  size.  The  knurled  ring  is  marked  with 
the  respective  sizes,  and  on  the  ends  are  stamped  "Go"  and 
"Not  go."  Now  these  little  words  tell  at  a  glance  which  way  the 
gage  is  to  be  turned,  but  we  think  the  words  are  not  sufficient. 


n  R 


No^Go 


O 


FIGS.  5,  6,  7,  and  8.  —  Limit  Gages. 


A  man  working  on  a  machine  picks  up  that  gage  and  uses  it, 
perhaps,  many  hundred  times  a  day,  and  without  taking  the 
trouble  to  look  at  the  lettering  he  will  try  it  on  the  work,  turning 
it  end  for  end,  may  be,  to  find  that  neither  end  will  go  on  the 
work.  Now  if  that  same  gage  was  made,  as  in  Fig.  7,  so  that 
the  large  end  marked  "Go"  was  distinguishable  in  form  from  the 
small  end,  the  man  manipulating  the  gage  would,  when  picking 
it  up,  naturally  turn  it  so  that  the  big  end  could  be  tried  first; 
if  that  would  not  go  on  he  would  know  it  would  be  useless  to  try 
the  other  side.  We  have  been  requested  by  several  men  to 
chamfer  one  of  the  edges  of  such  ring  gages  for  just  that  reason. 
There  are  some  limit  gages  made  as  shown  in  Fig.  8,  and  on  such 
it  is  not  necessary  to  follow  the  above  practice  as  their  position 
need  not  be  changed  to  discern  the  respective  sizes. 


GAGES  AND   GAGING   SYSTEMS 


COMBINATION  BENCH  GAGE 

Fig.  9  shows  a  small  combination  bench  gage  used  for  testing 
the  diameter  of  a  ball,  also  at  the  same  setting  showing  if  the 
hole  is  concentric  with  its  outer  diameter;  this  last  named  opera- 
tion is  accomplished  by  a  lever,  the  end  nearest  the  fulcrum 


FIG.  9. —  Combination  Bench  Gage. 

being  hardened,  ground  and  lapped  to  fit  the  hole  in  the  ball, 
while  the  other  end  multiplies  any  eccentricity  of  the  hole,  the 
ball  itself  being  held  central  by  a  snap  gage  fastened  on  the  main 
plate. 

DIFFERENT  FORMS  OF  PIN  GAGES 

Pin  gages  are  made  in  many  different  forms  and,  are  often 
used  as  limit  gages.     They  are  employed  mainly  in  gaging  sur- 


JL 


10.  —  Pin  Gage. 


faces  that  are  obscure  —  say  at  or  near  the  bottom  of  a  hole. 
Fig.  10  shows  such  a  gage  constructed  for  determining  the  depth 
of  a  hole.  It  is  composed  of  two  plates,  a  and  b,  which  are  cut 
away  so  that  they  will  have  a  three-point  bearing  in  the  hole; 
both  are  hardened  and  ground,  and  plate  a  has  a  tapped  hole 
through  its  center,  a  hole  in  which  the  handle  is  a  press  fit,  this 
handle  holding  both  plates  in  alignment.  The  three  pins  d  are 
hardened  and  lapped  at  both  ends,  and  there  is  a  small  collar  on 


i6 


GAGES  AND  GAGING   SYSTEMS 


each  against  which  the  spring  acts,  giving  them  a  downward 
pressure.  The  plate  b  has  its  outer  diameter  turned  and  ground 
so  that  it  fits  about  one  third  of  its  width  into  its  hole,  while  the 
remaining  part  rests  on  top  of  the  work.  The  top  face  of  b 
is  lapped  to  a  level  surface.  When  the  gage  is  placed  in  the 
hole  to  be  tested,  the  lower  ends  of  the  pins  come  in  contact  with 
the  bottom  of  the  hole,  and  by  a  little  pressure  on  the  handle 
the  upper  plate  is  then  forced  down  to  its  seat  on  the  work,  the 
pins  projecting  through  the  holes  in  this  plate,  unless  the  hole 
is  of  proper  depth,  when  the  tops  of  the  pins  must  be  perfectly 
level  with  the  top  face  of  b. 

Fig.  1 1  shows  another  style  of  pin  page,  this  one  being  con- 
structed for  gaging  the  recess  shown  in  the  accompanying  piece  of 
work.  It  is  composed  of  the  body  e,  which  is  hardened,  ground 
and  lapped  on  its  two  flanges,  and  has  a  straight  hole  through 


FIG.  ii.  —  Pin  Gage. 

its  center,  also  lapped  out,  to  receive  the  hardened  and  ground 
plug  /,  which  in  turn  has  an  eccentric  ground  on  one  of  its  ends, 
this  operating  the  gaging  pin  g  which  is  held  against  the  eccentric 
by  a  small  spring.  The  small  screw  b  engages  in  a  slot  milled 
into  /,  and  allows  the  latter  to  make  a  half  turn.  Secured  on  the 
end  of  /  is  a  knurled  head,  one  end  of  which  is  turned  to  form  a 
flange  whose  diameter  coincides  with  -the  end  of  e;  on  these  two 
flanges  are  zero,  or  limit  lines,  as  the  case  may  be.  The  location 
of  these  lines  is  governed  by  the  length  of  pin  g,  the  depth  of  the 
cut  to  be  gaged,  and  the  throw  of  the  eccentric. 

Fig.  12  shows  a  very  simple  gage  which  has  several  advantages, 
one  of  these  being  that  the  original  size  of  the  gage  can  never  be 
lost.  The  two  collars  ii  are  hardened,  ground  and  lapped  to  the 
required  thickness,  thus  the  size  of  the  gage  is  established  and 
can  be  maintained  with  very  little  trouble.  On  these  two  collars 
are  held  two  plates  of  hardened  steel,  one  side  of  each  being 
ground  and  lapped  and  this  side  resting  on  the  collars.  To  com- 


GAGES   AND  GAGING   SYSTEMS  17 

pensate  for  wear  the  hardened  plates  are  removed  and  relapped, 
so  that  they  will  be  perfectly  straight,  and  are  then  replaced 
without  in  any  way  affecting  the  gage  size. 

Lastly  we  endeavor  to  show  a  gage  that  is  extensively  used 
for  testing  the  size  and  parallelism  of  a  hole,  and  mainly  adapted 


FIG.  12. —  Simple  Test  Gage. 

for  holes  that  are  at  least  3  inches  in  diameter  and  of  unusual 
length.     Its  construction  is  as  follows: 

Part  ;',  Fig.  13,  is  a  head  into  which  screw  the  three  sleeves  k 
and  the  tube  /.  The  latter  is  a  piece  of  seamless  steel  tubing 
carefully  straightened,  and  with  one  end  bored  out  to  receive  the 
hardened  and  lapped  bushing  m,  and  the  other  end  bored  to 


FIG.  13.  —  Three-Point  Test  Gage. 

receive  the  micrometer  nut.  On  this  end  are  located  also  gradua- 
tions similar  to  those  on  a  micrometer.  One  end  of  rod  n  acts 
as  the  micrometer  screw,  while  the  other  end  is  hardened  and 
ground  and  lapped  to  a  running  fit  in  bushing  m;  this  same  end 
is  ground  and  lapped  off  to  a  perfect  45-degree  cone,  which  acts 
on  similar  ends  on  part  o,  serving  as  the  measuring  rods,  these 


i8 


GAGES  AND  GAGING   SYSTEMS 


being  hardened,  ground  and  lapped  and  the  largest  diameter 
fitting  in  the  hardened  and  lapped  bushing  p,  while  the  smaller 
part  slides  through  the  nut  q.  The  spring  r  tends  always  to  hold 
rods  o  against  n,  and  part  s  serves  to  hold  the  micrometer  end  of 
the  gage  in  alignment,  it  being  a  sliding  fit  on  tube  /. 

VARIATION  IN  SIZE  OF  WORK  DUE  TO  TYPE  OF  GAGE 

The  following  is  a  summary  of  some  experiments  made  in 
connection  with  a  limit  gage  system  shown  in  Fig.  14,  which  we 


FIG.  15.  — Plug  Gage, 


were  called  upon  to  lay  out  for  a  large  Austrian  iron  works.  The 
gages  were  to  range  from  6  millimeters  (|  inch)  up  to  250  milli- 
meters (10  inches);  but  we  decided  to  replace  the  heavy  and 
extensive  plug  gages,  Fig.  15,  with  the  cheaper  flat  bar  gage, 


FIG.  1 6.  — Flat  Gage. 


Fig.  1 6,  in  sizes  from  2j  to  6  inches,  and  with  the  spherical  end 
rod  gages,  Fig.  17,  in  sizes  from  6  to  10  inches. 

Having  grown  cautious  by  experience  in  the  shop,  we  made 
trials  of  2^-inchx  holes  with  all  three  kinds  of  gages  after  the 
following  plan: 

Three  holes  of  nominally  the  same  size  — 2  J  inches  — were 
commercially  made:  Hole  i  to  a  plug  gage,  Fig.  15;  Hole  2  to  a 
flat  gage,  Fig.  16;  Hole  3  to  a  rod  gage,  Fig.  17.  Hole  i  was  so 
made  that  the  go-in  end  of  the  plug  gage  passed  with  a  good 
sliding  fit,  feeling  friction  all  over.  It  is  generally  assumed  in 
such  cases  that  the  hole  must  be  at  least  0.005  millimeter  (about 


2,  5.  S.  S    S.  2.  S    3    2.  8   §    S    8    8   S    §   §  S          8  §    § 

QOOOOO       O O       0000       0000000000 


w 

m 


5.s 
I 

4- 

!   a 
s 


- 


-s— 


J 


1 1 1  &  3- 


5-5- 


3.  2-  § 


20  GAGES  AND  GAGING   SYSTEMS 

0.0002  inch)  larger  than  the  gage.  When  the  same  hole  i  was 
tested  by  the  flat  gage,  the  go-in  end  of  this  gage  fell  easily  through 
it,  and  the  rod  gage  passed  still  more  easily,  whereas  the  small 
end  of  the  flat  gage  goes  into  hole  3,  an  absolute  proof  that  the 
difference  between  a  plug  gage  and  its  hole  must  be  greater  than 
is  generally  supposed.  To  be  sure,  larger  new  gages,  Figs.  16, 
17,  were  made,  till  we  felt  the  same  friction  by  putting  them 
by  hand  through  hole  2,  and  found  that  they  ought  to  be  made 
0.012  millimeter  in  the  case  of  Fig.  16,  and  0.02  millimeter  in  the 
case  of  Fig.  17,  larger  than  the  corresponding  plug  gage. 

The  gage  system  shown  in  Fig.  14  was  consequently  laid  out 
with  the  flat  and  rod  gage  dimensions  increased  in  reference  to 
the  plug  gage  measurements,  as  illustrated  by  the  broken  line. 
The  starting  point  for  the  system  in  question  was  the  standard 
shaft;  it  was  decided  to  provide  hole  gages  only  for  running  fits 
and  for  push  fits,  or  those  that  could  be  entered  by  hand  or  by  a 


Spherical  End 

FIG.  17 

wooden  block,  that  is,  a  good  sliding  fit.  There  was  a  very  little 
need  for  keying  and  force  fits. 

At  the  same  time  we  found  by  sharp  inspection  by  the  flat 
and  rod  gages,  that  almost  all  holes  were  oblong,  i.e.,  they  had 
different  diameters  in  different  panels.  This  cannot  be  discov- 
ered by  a  plug  gage,  but  a  plausible  reason  is  the  fact  that 
the  plug  gage  did  not  enter  -where  the  others  did.  The  whole 
thing  is  not  at  all  astonishing,  because  everbody  knows  that  the 
finest  touch  (and  at  the  same  time  the  most  difficult  measurement) 
is  made:  (I)  by  a  rod  gage  with  the  rounded  points,  point  touch; 
(II)  by  spherical  end  rods,  Fig.  17,  supposed  line  touch;  (III)  by 
flat  gages,  Fig  16,  supposed  small  surface  touch;  (IV)  by  plug 
gages,  Fig.  1 5,  supposed  cylinder  surface  touch. 

We  say  "supposed"  because  by  consideration  the  touch  of 
each  group,  IV,  III,  II,  I,  must  go  back  respectively 'to  III,  II, 
I,  o;  for  it  is  obvious  that  each  gage  must  be  at  any  rate  smaller 
than  the  hole  to  be  tested,  and  consequently  the  two  circles  of 
hole  and  gage  are  eccentric,  and  reduce  the  touch  surface  to  lines, 


GAGFS  AND  GAGING  SYSTEMS 


21 


and  so  forth.  And  this  must  be  true  even  for  the  Whitworth 
plug  and  ring.  We  all  know  by  experience  how  difficult  it  is  to 
insert  a  plug  into  a  ring  of  the  same  size,  say  2%  inches.  It  is 
necessary  to  grease  both  with  the  best  vaseline,  and  if  we  succeed 
in  entering  the  plug  without  using  the  general  tool-maker's  trick 
of  talking  to  the  observer  while  warming  the  ring  in  the  mean- 
time by  the  hand,  we  always  see  afterwards  the  interference 
colors  in  the  grease,  an  evident  proof  that  there  was  no  metallic, 
but  a  grease  touch  between  plug  and  ring,  which  means  that  the 
ring  was  larger  than  the  plug.  No  one  risks  putting  them  to- 
gether dry;  there  is  no  doubt  the  surfaces  would  seize  one  another 

at  once. 

A 


FIG.  18.  —  Gage  for  Internal  Hole  Measurement. 


Finally,  we  inspected  the  standard  ring  by  the  end  rod,  which 
was  exactly  2j  inches  in  diameter,  and  found  a  much  easier  fit 
than  with  the  standard  (greased)  plug.  We  concluded,  conse- 
quently, that  in  general  manufacturing  the  irregularities  of  holes 
are  so  great  that  in  reality  for  2\  inches  in  diameter  we  get  holes 
of  about  0.02  millimeter  (0.007  inch)  larger  than  we  supposed. 
This  additional  factor  is  smaller  for  small  and  greater  for  great 
diameters. 

Because  we  started  with  the  Whitworth  plug  and  ring,  we 
tried  to  design  an  instrument  for  internal  hole  measurements, 
which  is  illustrated  in  Fig.  18.  The  tool  is  manufactured  by  the 
Loewe  Co.,  Berlin.  The  flattened  balls  a  which  serve  to  bring 


22  GAGES  AND  GAGING   SYSTEMS 

the  pressure  of  the  wedge  b  without  pinching  to  the  small  rods  c 
which  are  very  carefully  fitted  to  their  rods  without  play,  are  only 
intermediate  pieces  to  secure  a  correct  connection  of  the  different 
parts.  The  two  thumb-screws  serve  to  fix  the  end  pieces  for 
testing  snap  gages,  explained  later  on.  The  inclination  of  the 
wedge  is  i  to  100,  the  pitch  of  the  screw  d  is  i  millimeter,  and 
the  micrometer  head  has  100  divisions;  thus  we  can  read  o.oooi 
millimeter  change  in  the  distance  of  the  two  measuring  ends. 
The  original  distance  is  adjusted  by  a  measuring  machine,  and 
then  the  instrument  is  put  into  the  hole  and  readjusted,  until  the 
inspector  feels  the  touch.  At  the  end  the  increase  is  read  on  the 
scale  and  supervised  by  the  measuring  machine.  These  trials 
confirmed  the  first  conclusions.  For  measuring  holes  the  pieces 
c  have  spherical  ends  instead  of  flat  ones.  The  diameter  of  the 
sphere  to  which  the  ends  are  ground  corresponds  to  the  smallest 
hole  to  be  measured.  Because  the  holes  are  always  larger  than 
this  the  inside  walls  of  the  hole  are  always  touched  by  the  center 
and  never  by  the  corners  of  the  pieces  c.  The  spherical  rounding 
with  great  diameter  has  been  done  for  convenience  to  superin- 
spection  on  the  measuring  machine.  With  flat  end  rods  inserted, 
the  instrument  is  very  useful  to  replace  in  the  tool-room  very 
expensive  sets  of  end  pieces  or  combination  rods  for  testing  snap 
gages  of  limit  systems  having  different  allowances  but  the  same 
nominal  size.  Of  course,  the  measuring  machine  is  an  indis- 
pensable complement  to  this  sort  of  gage. 

SOME   GAGING  AND  MEASURING  METHODS  AT  THE  WORKS  OF 
THE  WESTINGHOUSE  MACHINE  COMPANY 

The  basis  of  all  shop  gaging  done  at  these  works  is  an  8- 
foot  Pratt  &  Whitney  measuring  machine,  with  which  standard 
exact  inch  rod  gages  have  been  made  as  required  until  the  works 
have  a  complete  set  of  whole  inch  lengths  up  to  80  inches.  These 
rods  are  used  for  adjusting  caliper  gages,  shown  in  Fig.  19,  all  of 
which,  except  the  micrometer  heads,  are  home  made.  In  making 
these  calipers  a  good  deal  of  care  is  given  to  obtaining  exact 
alignment  of  the  micrometer  head  and  the  anvil  screw,  but  other- 
wise they  are  of  e very-day  workmanship.  The  anvil  screw  has 
considerable  range  of  adjustment,  and  the  calipers  shown  as  hav- 
ing an  I-beam  section  of  yoke  —  which  form  a  set  by  themselves 


GAGES  AND  GAGING   SYSTEMS 


FlG    ig._Test  Rods  and  Caliper  Gages. 


24  GAGES  AND   GAGING   SYSTEMS 

—  giving  thus  a  range  from   10  to  40  inches  by  the  following 
intervals: 


No. 

Inches 

i, 

10-14 

2, 

14-18 

3> 

18-22 

4. 

22-26 

5> 

26-30 

6, 

30-35 

7> 

35-40 

The  anvil  screws  have  bastard  threads,  10  per  inch,  though 
Mr.  Thomas,  to  whom  these  gages  are  due,  thinks  that  were  he  to 
make  the  set  again  he  would  make  the  pitch  20  per  inch  instead 
of  10.  As  these  are  used  only  for  adjusting  the  instruments  so 
that  the  micrometer  heads  will  read  zero  for  the  even  inches, 
they  are  of  ordinary  lathe  cut  accuracy  only.  The  holes  in  the 
yoke  end  for  these  screws  are  not  threaded,  but  are  bored  a  neat 
sliding  fit,  the  nuts  being  half  nuts  only  and  arranged  to  be  clamped 
to  the  screws,  or  quickly  disengaged  by  turning  a  knurled  nut 
recessed  into  and  projecting  through  the  web  of  the  I-section. 
This,  of  course,  saves  a  lot  of  traversing  of  the  screw  when  it  has 
to  be  moved  a  considerable  distance.  The  yokes  are  made  of 
zinc-aluminum  alloy,  and  are  surprisingly  light.  The  mixture 
is  of  30  parts  zinc  to  70  aluminum,  and  the  castings  were  made 
in  the  brass  foundry  of  the  works  without  difficulty. 

For  the  delicacy  of  action  a  caliper  gage  must  of  course  be  stiff. 
When  made  of  steel  or  iron,  however,  there  is  increase  of  weight, 
and  while  the  stiffness  is  a  necessity,  the  weight  is  objectionable 
because  it  dulls  the  sense  of  touch.  The  lightness  of  these  in- 
struments is  such  that  the  largest  size  may  be  handled  by  one 
man  with  perfect  ease,  and  in  connection  with  the  appliances  to 
be  described,  the  gaging  of  the  largest  shafts  is  done  by  one  man 
and  of  course  with  far  greater  satisfaction  than  would  be  possible 
with  two  men  on  opposite  sides  of  the  shaft  being  gaged.  Those 
whose  experience  is  limited  to  caliper  gages  of  steel  can  hardly 
appreciate  the  advantage  which  decreased  weight  gives.  The 
calipers  are  handled  with  one  hand,  and  the  contact  of  the  measur- 
ing points  with  the  piece  being  gaged  is  felt  with  the  same  deli- 
cacy and  certainty  that  is  customary  with  smaller  work. 


GAGES  AND  GAGING   SYSTEMS  25 

The  method  of  using  these  instruments  is  unique.  An  end 
measure  rod  surrounded  by  a  wooden  case  is  supported  in  a 
vertical  position  by  a  stand  having  a  heavy  base.  Clamped  to 
the  upright  of  the  stand  is  a  support  for  two  helical  springs  which 
support  a  stirrup  having  a  hole  through  its  center,  through  which 
the  anvil  screw  of  the  caliper  is  passed.  The  springs  hold  the 
anvil  screw  in  gentle  contact  with  the  lower  end  of  the  measure 
rod,  which  in  this  case  is  39  inches  long,  and  by  adjusting  the 
anvil  screw  the  micrometer  head  is  made  quickly  to  read  zero 
when  the  micrometer  head  screw  contacts  with  the  upper  end  of 
the  end  measure  rod.  Should  the  desired  size  be  a  few  thou- 
sandths above  the  even  inch  dimension  for  a  force  fit,  or  a  few 
thousandths  below  for  a  running  fit,  or  should  it  be  desired  to 
add  any  friction  of  an  inch  to  the  length  of  the  end  measure  rod, 
the  required  amount  is  added  by  the  graduations  of  the  microm- 
eter head  when,  after  clamping  the  head,  the  instrument  is  set 
for  use. 

The  actual  gaging  of  a  39-inch  shaft  in  the  lathe  is  accomplished 
in  the  manner  described  in  the  following:  Two  light  sling  chains 
surround  the  shaft  and  support  a  pair  of  springs  similar  to  those 
of  the  end  measure  rod  stand,  these  springs  again  supporting  a 
stirrup  which  holds  the  anvil  screw  in  contact  with  the  shaft  to 
be  measured  as  the  previous  one  held  it  against  the  end  measure 
rod.  Held  in  this  way  and  with  the  extreme  lightness  of  the 
yoke,  the  gaging  may  be  done  with  the  highest  degree  of  satis- 
faction. 

The  reader  will  understand  that  all  uncertainties  regarding 
deflection  of  the  instrument  by  its  own  weight  are  eliminated  by 
its  method  of  support.  Its  position  is  the  same  —  vertical  - 
when  being  adjusted  as  when  being  used,  and  the  support  is  at 
the  same  point.  Within  the  set  of  calipers  (Fig.  19)  which  have 
been  described,  two  others  will  be  seen  which  are  made  of  sheet 
aluminum  instead  of  alloy,  and  which  by  reason  of  their  extreme 
lightness  are  found  to  be  more  sensitive  than  the  others.  The 
one  on  the  left  is  shown  arranged  for  gaging  bored  holes,  the 
yoke  being  very  convenient  for  this  class  of  work,  as  the  instru- 
ments may  be  used  with  the  boring  bar  still  in  place. 

At  the  left  is  a  cheap  but  very  effective  instrument  for  use  in 
gaging  such  pieces  as  pistons,  for  which  the  full  depth  of  yoke  is 
not  needed.  The  beam  is  of  wood,  and  the  sliding  heads  of  zinc- 


26  GAGES  AND  GAGING   SYSTEMS 

aluminum  alloy  as  with  the  full  yoke  form.  In  this  instance  the 
heads  were  first  made  of  bronze,  but  their  weight  caused  them  to 
be  discarded  without  fitting  them  up. 

On  the  floor  below  the  large  case  will  be  seen  a  set  of  Starrett 
inside  micrometers,  with  a  full  set  of  extension  pieces.  These 
are  of  course  used  for  gaging  holes. 

In  the  lower  right-hand  corner  of  the  large  case  is  an  appliance 
for  gaging  T-headed  shrink  links  for  securing  fly-wheel  segments. 
Fig.  20  shows  roughly  two  segments  of  such  a  wheel,  the  faces  a 
being  machined.  The  spring  b  on  the  bolt  c  clamps  the  jaws 
with  sufficient  firmness  to  hold  them  in  position,  and  an  inside 
micrometer  d  quickly  gives  the  distance  between  the  faces,  from 
which  the  deduction  of  the  specified  number  of  thousandths  for 
the  shrinkage  allowance  gives  the  length  of  the  link. 

Resting  on  the  bottom  of  the  case  and  to  the  left  of  the  center 
is  a  peculiar  gage  for  the  seats  of  double-beat  poppet  valves, 
which  should  be  not  only  of  the  correct  diameter  and  taper  but 
also  correct  with  relation  to  one  another.  The  sharp  taper  of  the 
gage  will  be  understood  from  the  fact  that  the  bores  for  which 
they  are  intended  are  for  the  insertion  of  additional  or  ''false" 
seats  on  which  the  valves  act.  The  method  of  using  this  gage 
is  shown  in  Figs.  21  and  22.  The  upper  seat  is  first  bored  until 
the  upper  gage  bar  —  detached  from  the  remainder  of  the  gage 
-fits  it  as  shown  in  Fig.  21,  the  upper  edge  of  the  gage  bar 
being  flush  with  the  faced  seat  a  of  the  casting.  This  seat  bored, 
the  parts  of  the  gage  are  assembled,  the  connecting  pins  being  a 
snug  fit  in  the  holes,  and  the  lower  seat  is  bored  until  the  upper 
gage  bar  again  fits  the  upper  seat,  the  lower  one  fitting  its  seat 
also  as  in  Fig.  22,  when  the  relation  of  the  two  bores  is  obviously 
the  same  as  that  of  the  two  gage  bars. 

Standing  vertically  on  the  bottom  of  the  large  case  and  near 
the  center  (Fig.  19)  are  two  carefully  made  strips  of  steel,  each 
with  an  upturned  end,  and  with  a  row  of  holes  down  the  center 
spaced  one  inch  apart.  These  are  for  use  in  gaging  taper  pieces 
for  forced  fits,  for  in  the  Westinghouse  Machine  Company's  works 
many  forced  fits  are  taper,  the  taper  used  being  approximately 
yV  inch  per  foot  measured  on  the  diameter.  Fig.  23  shows  the 
method  of  using  these  strips  in  connection  with  an  inside  mi- 
crometer, the  taper  being  greatly  exaggerated.  The  measure- 
ments are  not  made  perpendicular  to  the  axis,  but  to  one  side 


28  GAGES  AND  GAGING   SYSTEMS 

of  the  bore.  One  point  of  the  micrometer  being  held  by  a  hole  in 
the  strip,  the  other  is  manipulated  precisely  as  though  the  bore 
were  straight,  as  indicated  by  the  dotted  arc;  and  the  frequent 
spacing  of  the  holes  in  the  strip  enables  the  bores  to  be  tested 
for  uniformity  of  taper  throughout  its  length.  The  dimension 
used  measured  in  this  way  is  the  one  given  on  the  drawing  as  the 
true  diameter  —  the  microscopic  difference  between  the  dimen- 
sion as  called  for  and  as  made  being  obviously  of  no  importance. 
Mr.  Thomas  has  much  simplified  the  gaging  of  these  taper 
holes  by  a  —  and  otherwise  unimportant  —  change  from  the 
former  taper  of  -jV  incn  per  foot  leads  to  decimals  for  the  diameter 
of  one  of  the  ends  and  for  most  of  the  intermediate  inches.  Thus 
a  hole  of  10  inches  diameter  at  the  large  end,  and  having  a  taper 
of  -IQ  inch  per  foot,  will  have  the  following  diameters  at  successive 
inches  of  length  when  carried  out  to  four  places  of  decimals: 

9.9948 
9.9896 
9.9844 
9.9792 
9.9740 
9.9688 

By  changing  the  taper  to  .005  per  inch  (-^Q  inch  per  foot  is 
equal  to  .005208  per  inch)  the  values  become: 

9-995 
9.990 

9.985 
9.980 

9-975 
9.970 

The  change  in  the  taper  thus  gives  round  figures  for  each 
inch  of  length,  and  the  second  set  of  figures  is  obviously  much 
more  easily  read  from  the  micrometer  than  the  first,  and,  by 
subtracting  from  the  large  diameter  half  as  many  hundredths  as 
the  piece  has  inches  of  length,  the  small  diameter  is  obtained 
directly,  whereas  with  a  taper  of  yV  incn  Per  foot,  the  small  di- 
ameter can,  in  most  cases,  be  found  only  by  calculation.  One 
advantage  of  the  taper  forced  fit  is  not  recognized  as  often  as  it 


GAGES  AND  GAGING  SYSTEMS 


29 


should  be.  With  a  parallel  fit  the  holes  can  be  compared  only 
by  gaging,  whereas  with  the  taper  fit  the  plug  may  be  in  its  seat 
and  the  two  compared,  the  distance  remaining  for  pressing  home 
when  the  parts  come  to  contact  forming  the  best  possible  check 
upon  both.  Thus  with  a  taper  of  .005  per  inch  and  an  allowance 
of  .01  for  pressing  the  plug  should  enter  the  hole  within  two  inches 
of  going  home.  The  adoption  of  the  .005  inch  taper  simplifies 
this  relation  as  well  as  the  gaging,  as  by  using  this  taper,  the  num- 
ber of  inches  by  which  the  parts  should  not  go  home  when  as- 
sembled is  one  inch  for  each  five-thousandths  of  pressing  allowance. 
Fig.  24  shows  a  form  of  gage  for  smaller  taper  holes,  such  as 
those  for  cross-head  pins,  which  Mr.  Thomas  prefers  to  a  full  plug. 
They  are,  of  course,  much  lighter  than  full  plugs,  and  with  them 


FIG.  24.  —  Gage  for  Small  Taper  Holes. 

the  holes  can  be  gaged  independently  on  different  diameters, 
while  irregularities  in  the  holes  are  more  easily  detected. 

Fig.  25  shows  a  very  simple  method  of  testing  the  accuracy 
of  the  pitch  of  taps.  The  upper  view  shows  that  the  half  nut 
has  but  two  threads,  and  by  laying  the  tap  in  the  half  nut  in 
two  positions,  which  by  the  supposed  pitch  should  be  an  inch 
apart,  and  then  measuring  the  distance  with  the  micrometer 
head,  the  error  may  be  found  and  measured. 

Mr.  Thomas  finds,  as  others  have  found,  that  with  the  best 
outfit  of  gages,  the  old-fashioned  calipers  still  have  their  place, 
and  Fig.  26  shows  such  a  caliper  of  large  size  and  made  of  sheet 
aluminum.  This  instrument  has  a  capacity  over  a  full  circle  of 
65  inches  and  its  weight  is  but  8|  pounds.  Mr.  Thomas  calls  it 
an  articulated  caliper  from  the  construction  of  the  contact  ends. 
These  are  jointed  to  the  jaws  so  as  to  present  faces  squarely  to 


GAGES  AND  GAGING  SYSTEMS 


the  work,  and  one  of  the  contact  points  is  adjustable  by  a  fine 
knurled  head  screw,  this  screw  being  used  for  the  fine  adjustment 
of  the  instrument. 


FIG.  25. —  Testing  Taps. 

LIMIT  GAGE  PRACTICE  AT  THE  WORKS  OF  LUDW.  LOEWE  &  Co. 

We  insert  the  accompanying  diagram  (Fig.  27)  of  limit  gage 
practice  at  the  Loewe  shops,  Berlin,  Germany.     The  illustration 


0,04 


10  16  26       40 


100  150  200 

Diameter  mm. 
FIG.  27.  —  Diagram  of  Limit  Gage  System. 


is  a  greatly  magnified  representation  of  the  difference  between  a 
series  of  shafts  and  holes  when  adapted  to  different  classes  of 
fits.  The  abscissas  give  the  nominal  diameters.  On  each  side 


GAGES  AND  GAGING   SYSTEMS  31 

of  the  nominal  size  are  descending  and  ascending  lines,  which  by 
their  distances  denote  the  allowances  for  running  and  push  fits. 
This  diagram,  while  printed  in  the  place  we  find  it  mainly  for 


FIG.  26.  —  Large  Size  Aluminum  Caliper. 

illustrative  purposes,  may  reasonably  be  taken  to  agree  quanti- 
tatively with  the  practice  of  the  Loewe  firm,  which  has  established 
its  standards  by  long  experiments  and  experience. 


32  GAGES   AND   GAGING    SYSTEMS 

USE  OF  GAGES  AND  INDICATORS  IN  JIG  AND  FIXTURE  WORK 

Without  a  doubt  the  "button  method"  of  indicating  holes  in 
drill  jigs  is  one  of  the  most  accurate  that  has  ever  been  found,  as 
it  has  come  to  be  one  of  the  most  universal  methods  in  use;  but 
there  are  many  shops  in  which  the  use  of  this  system  is  confined 
to  the  use  of  buttons  on  work  that  can  be  swung  in  a  lathe. 
When  the  method  has  been  learned  thoroughly,  its  usefulness 
will  be  appreciated  for  all  available  work,  not  only  such  as  can 
be  swung  in  the  lathe,  but  also  on  work  that  is  too  large  for  the 
lathe  and  which  must  be  done  in  the  milling  machine.  For  this 
class  of  work  a  special  indicator  is  necessary  for  setting  the  but- 
ton in  perfect  alignment  with  the  milling  machine  spindle.  An 
example  of  the  usefulness  of  the  button  method  may  be  found  in 
a  large  leaf  drill  jig  for  the  side  frame  plates  of  a  cash  register, 
with  numerous  bushing  holes  in  the  leaf,  which  is  too  large  to 
swing  in  the  lathe.  The  location  of  the  holes  could,  no  doubt, 
be  accurately  accomplished  in  several  ways,  of  which  the  block 
method  is  one.  By  this  method  a  square  block,  with  a  hole 
accurately  though  its  center,  is  located  on  the  leaf  by  its  outer 
sides,  clamped  in  position  and  used  as  a  jig  bushing  for  the  drill. 
We1  cannot  say  that  we  admire  this  method  as  it  invites  an  error 
to  be  made  too  easily. 

Another  method  would  consist  of  placing  the  leaf  on  the  mill- 
ing machine  and  using  the  graduated  dials  of  the  machine,  but 
this  method  seldom  gives  accurate  results,  especially  after  the 
screws  have  become  worn  through  use.  No  doubt  there  are 
many  more  methods  that  could  be  mentioned,  but  we  think  that 
there  is  no  method  more  accurate  than  the  use  of  the  buttons 
and  indicator  shown  in  Fig.  28. 

INDICATING  GAGE  FOR  USE  ON  MILLING  MACHINE 

The  leaf  of  the  jig  is  first  "buttoned  up,"  this  being  a  familiar 
shop  term  used  when  applying  the  buttons  to  a  piece  of  work. 
It  is  needless  to  go  into  details  about  buttoning  up  work,  as  that 
has  been  fully  and  thoroughly  described  in  our  treatise  entitled 
"American  Tool  Making."  After  this  is  accomplished,  the  leaf 
is  placed  on  the  milling  machine  against  an  angle  plate,  to  which 
it  is  held  by  clamps,  as  shown  in  Fig.  29.  The  indicator  is  then 
placed  in  the  spindle  of  the.  machine  and  applied  to  a  button, 


34 


GAGES   AND   GAGING   SYSTEMS 


thus  truing  it  perfectly  with  the  center  of  the  spindle,  after  which 
the  hole  is  made  with  drill  and  boring  bar. 

The  buttons  most  generally  used  are  made  as  shown  in  Fig. 
30.     They  are  hardened,  ground  and  lapped  to  fit  a  ring  gage, 


FIG.  29. —  Use  of  Indicator  in  Milling  Machine. 

i  inch  in  diameter  being  a  convenient  size.  As  will  be  seen  from 
Fig.  29,  the  angle  plate  rests  on  two  special  parallels,  which  in 
turn  are  bolted  to  the  milling  machine  table.  The  object  of 
letting  the  angle  plate  project  over  the  side  of  the  table  on  the 


GAGES  AND   GAGING   SYSTEMS  35 

parallels  is  to  permit  the  insertion  of  the  tool  in  place  of  the  in- 
dicator without  disturbing  the  longitudinal  position  of  the  table, 
the  tools  being  inserted  by  the  use  of  the  cross-feed  screw. 

The  indicator  is  shown  in  Fig.  28.  The  shank  b  is  fitted  to  a 
Brown  &  Sharpe  small  taper.  On  this  shank  is  milled  a  tongue 
which  fits  into  part  a,  and  is  graduated  to  facilitate  setting  the 
instrument  to  describe  a  circle  of  any  diameter  from  o  to  4  inches. 
When  the  zero  mark  on  a  is  in  line  with  a  similar  mark  on  b,  the 
point  of  the  indicator  lever  which  comes  in  contact  with  the  work 
will  revolve  on  the  center.  There  are  eight  graduations  on  each 


FIG.  30. —  "Buttons"  for  Jig  Work. 

side  of  zero,  each  line  giving  J-inch  movement;  that  is,  to  describe 
a  £-inch  circle  the  zero  line  on  a  would  have  to  be  set  in  line  with 
the  first  line  from  the  zero  on  b,  and  similarly  the  other  figures  on 
b  denote  the  circle  the  point  will  describe.  The  tongue  and 
groove  joint  is  held  firm  by  the  knurled  nut  and  bolt  g  and  i. 
The  body  of  a  is  slotted  through  its  center  to  receive  the  two 
levers  e  and  d,  which  swing  on  small  pivot  screws  b  having  60- 
degree  points.  A  small  and  delicate  spring  /  tends  to  hold  lever  e 
to  zero  on  the  graduated  plate  c,  and  also  gives  pressure  against 
lever  d,  which  in  turn  acts  on  the  work.  A  little  stop-pin  above 


o 


FIG.  31.  —  Shank  for  Indicator. 

lever  d  holds  the  levers  in  position  when  at  rest.  A  detail  sketch 
of  lever  e  shows  the  index  to  be  forked  to  read  against  graduations 
on  both  sides  of  the  arc  plate  c.  This  double  graduation  permits 
readings  to  be  taken  from  either  side,  as  the  indicator  turns  over 
with  the  machine  spindle.  The  indicator  can  be  used  to  true  up 
a  hole  as  well  as  a  projection,  and  it  can  also  be  used  to  good 
advantage  in  the  drill  press  or  lathe  by  placing  the  shank  b  into 
a  round  rod  shown  in  Fig.  31. 

We  have  also  seen  another  method  in  use  for  locating  work  on 
the  milling  machine,  which,  however,  is  not  as  accurate  as  the 


GAGES  AND  GAGING  SYSTEMS 


indicator.  We  refer  to  the  arbor  and  bushing  shown  in  Fig.  32. 
The  arbor  has  its  end  ground,  and  lapped  to  the  same  size  as  the 
buttons,  and  a  knurled  ring  is  lapped  out  a  nice  sliding  fit  on  the 
arbor.  By  placing  the  arbor  in  the  machine  spindle  and  bringing 
the  jig  button  close  to,  and  in  line  with  it,  so  that  the  knurled 
ring  will  slip  over  the  button,  it  is  certain  to  bring  both  arbor 
and  button  in  line.  The  trouble  with  this  method  lies  in  the 
failure  of  the  arbor  to  always  run  true  with  the  spindle.  Should 
a  bit  of  dirt  get  between  the  arbor  and  spindle,  as  is  often  the 
case,  or  should  the  spindle  hole  not  be  dead  true,  the  arbor  would 
not  be  true  with  the  spindle,  and  an  error  would  result  in  locating 
the  work. 


FIG.  32.  —  Arbor  and  Bushing  for  Jig  Work. 

VERNIER  METHOD  OF  LOCATING  WORK  ON  MILLING  MACHINE 

Another  good  method  that  can  be  used  for  accurately  locating 
distances  on  the  milling  machine  is  shown  in  Figs.  33  and  34. 
Accuracy  is  obtained  by  using  a  Brown  &  Sharpe  vernier  caliper 
beam  and  vernier  plate  instead  of  the  graduated  disks.  On  the 
milling  machine  table  a,  and  into  the  T-slot,  which  is  intended 
for  the  feed-tripping  studs,  two  bolts  marked  b  are  placed.  They 
project  out  beyond  the  nuts  which  hold  them  in  position  about 
ij  inches,  this  outer  part  having  been  turned  to  the  size  of  the 
root  of  the  thread,  and  part  of  it  flattened  off  to  act  as  a  resting- 
place  for  the  vernier  caliper  beam  c,  which  is  held  in  position  by 
two  small  straps  and  screws  /.  The  forging  g  is  held  in  position 
by  utilizing  the  forward  bolt  and  nut  To,  that  serve  to  bind  the 
swiveling  part  of  the  machine.  On  the  top  end  of  g  the  adjustable 
block  e  is  held  by  a  dovetail  milled  in  g,  and  a  slot  and  small 
binding  bolt  i.  On  this  block  e  is  secured  the  vernier  plate  d. 
As  can  be  readily  seen  by  running  the  table  to  and  fro,  and 
recording  the  measurements  from  the  vernier,  accurate  measure- 
ments can  be  made.  Accurate  up-and-down  measurements  are 
made  bv  a  little  extra  device  clamped  to  the  column  of  the 


GAGES  AND  GAGING  SYSTEMS 


37 


H  ;      '.  \?       ;."'/'     4 

M  i|  ''i;!::'li: I:"!,  i  '  UttUM '  '•  U  !  J  \ '  ''  ^ . ''  "  ''^  •  '  J.lt  UM  > 


FIGS.  33  and  34.  — Milling  Machine  Practice. 


38  GAGES  AND   GAGING   SYSTEMS 

machine  and  end  measurement  rods  of  such  lengths  as  the  job 
required,  these  rods  being  used  between  the  knee  of  the  machine 
and  the  part  clamped  on  the  column.  One  more  little  kink  and 
this  method  is  complete:  By  binding  a  piece  of  wire  around  g, 
having  a  loop  above  to  hold  a  magnifying  glass,  easy  and  accurate 
reading  is  obtained.  This  last-named  method  is  limited  in  range 
and  accuracy  by  the  length  and  accuracy  of  the  vernier. 

BORING  MASTER  GAGE  PLATES  FROM  MODELS 

Accurate  tool  and  gage  work  is  required  in  most  factories  at 
the  present  time,  as  the  interchangeable  system  of  manufacturing 
calls  for  it,  especially  where  they  require  the  most  accuracy.  It 
is  always  advisable  to  make  the  model  first,  then  the  gages,  and 
last  the  tools.  If  tools  and  gages  are  made  to  models  instead  of 
drawings,  as  in  many  shops,  it  is  absolutely  necessary  to  make 
the  gages  first,  in  order  that  they  may  be  perfect  to  the  model, 
as  fitting  the  model  to  jigs,  fixtures  and  other  tools  may  interfere 
with  the  accuracy  of  the  model.  There  are  some  very  good 
systems  in  some  of  our  large  shops  for  holding  everything  to 
standard.  By  one  method  the  first  step  is  to  make  a  model 
machine  which  is  as  nearly  perfect  as  mechanical  skill  can  make 
it.  When  complete  it  is  assembled  to  see  if  it  is  perfect  in  all 
details,  and  if  found  perfect  it  is  taken  apart  and  the  gages  are 
made  to  fit  the  parts  in  the  most  accurate  manner.  Three  sets 
of  duplicate  gages  are  always  made,  one  of  which  goes  to  the 
inspecting  department,  the  second  to  the  manufacturing  depart- 
ment, and  the  third  is  held  in  reserve  and  only  used  as  reference 
or  master  gages.  This  last  set  acts  as  a  tell-tale  to  all  mistakes, 
and  as  a  standard  for  working  gages  or  tools  that  may  need  re- 
newal at  any  future  time.  Among  these  master  gages  are  master 
plates,  which  serve  to  hold  standard  the  size  and  location  of  a 
number  of  holes.  A  very  neat  way  to  make  such  master  plates 
is  as  follows:  Plane  or  grind  a  piece  of  steel  so  that  it  will  be  per- 
fectly parallel  and  about  f-inch  thick.  Clamp  it  to  the  model  piece 
opposite  the  side  on  which  the  holes  in  the  model  were  located, 
with  a  thin  piece  of  steel  between  model  and  master  plate,  so  that 
when  boring  the  holes  in  the  plate  no  damage  will  be  done  to  the 
model  (see  Fig.  35).  Fit  a  piece  of  steel  to  the  spindle  of  the 
lathe,  as  though  it  were  to  be  a  live  center,  allowing  it  to  project 


GAGES  AND  GAGING   SYSTEMS 


39 


beyond  the  face-plate  far  enough  to  be  turned  off  a  perfect  fit  to 
the  largest  hole  in  the  model.  Care  should  be  taken  that  the 
face-plate  runs  perfectly  true.  After  turning  the  stud  to  a  per- 
fect fit  for  the  first  hole,  the  model  with  the  master  plate  is  slid 
on  and  clamped  to  the  face-plate.  The  first  hole  in  the  master 
plate  is  then  bored  with  an  allowance  of  .002  for  grinding  after 
the  master  plate  is  hardened.  For  the  second  hole  select  the 
next  size  smaller  so  that  the  same  stud  will  answer  for  all  five 
holes,  and  proceed  as  before,  care  being  taken  to  have  the  master 
plate  securely  fastened  to  the  model  to  avoid  any  chances  of 
slipping.  After  boring  all  holes  in  this  manner  the  plate  is  ready 


FIG.  35.  —  Boring  Holes  in  Master  Plate. 

for  hardening.  After  hardening  the  plate  is  replaced  on  the 
model  and  the  holes  are  ground  out  to  within  .0003,  which  is  left 
for  the  final  lapping  to  size.  Fig.  36  shows  the  work  as  swung  in 
the  lathe.  Time  may  be  saved  by  making  the  stud  in  two  pieces, 
as  in  Fig.  37,  thus  saving  the  repeated  fitting  of  the  taper.  The 
right-hand  piece  is  soldered  into  the  sleeve  and  turned  off  to 
form  the  stud,  which,  of  course,  is  always  turned  off  in  position. 

MAKING  MASTER  PLATES  FOR  WATCHES 

In  making  master  plates  for  watches,  electric  instruments, 
clocks  and  similar  work,  in  which  the  holes  in  the  side  plates  are 
to  be  held  to  a  standard  for  the  train  of  gears,  and  the  holes  are 


GAGES  AND   GAGING   SYSTEMS 


too  small  to  grind  out  after  the  master  plate  is  hardened,  it  is 
good  policy  to  bore  such  holes  larger  than  the  holes  in  the  model, 
and  after  the  master  plate  is  hardened,  grind  the  holes  out  with 
a  diamond-charged  lap  used  in  the  same  manner  as  an  internal 
emery  wheel.  The  holes  are  then  bushed,  the  bushing  being 
hardened  and  lapped  to  the  same  size  as  the  holes  in  model.  A 
little  piece  of  hardened  drill  rod  is  then  placed  in  the  spring  chuck 
of  a  bench  lathe,  and  ground  to  fit  the  hole  in  the  bushing.  The 
bushing  is  then  slipped  on  and  ground  and  lapped  to  a  press  fit 


Master  Plate 


FIG.  36.  —  Jig  Work  in  Lathe. 

in  the  master  plate,  care  being  taken  that  the  press  fit  is  not  so 
tight  as  to  interfere  with  accuracy  of  plate. 


FIG.  37.  —  Stud  for  Jig  Work. 

USE   OF   GAGES  AND    INDICATORS   IN   ACCURATE    INDEX   PLATE 

MAKING 

Making  index  plates  seems  but  a  small  item,  which  no  doubt 
it  is,  providing  no  accuracy  is  attached  to  it ;  but  where  accuracy 
is  essential,  it  becomes  quite  a  different  task.  It  has  fallen  to  a 
tool-maker's  lot  to  make  several  such  plates  in  which  accuracy 
was  required.  His  first  plate  was  to  have  six  notches  for  the 
index  finger,  and  he  attempted  to  make  it  in  the  milling  machine, 
depending  on  a  careful  use  of  the  dividing  head;  but  when  he 
proved  it  up  he  found  an  error  of  .005  in  the  spacing.  Thinking 


GAGES  AND   GAGING   SYSTEMS  41 

the  dividing  head  might  be  at  fault  he  tried  another  and  found 
about  the  same  error.  Ultimately  he  tested  seven  heads  but 
could  not  get  an  accurate  plate,  and  came  to  the  conclusion  that 
he  must  contrive  a  more  accurate  method. 

His  first  method  gave  very  good  results,  but  it  necessitated 
the  making  of  two  plates  and  a  lot  of  hand  work.  This  method 
was  as  follows:  Duplicate  plates  were  placed  on  a  hardened  and 
ground  arbor,  and  cut  in  the  milling  machine  between  centers 
with  the  most  accurate  dividing  head  at  hand,  one  side  of  slot 
being  radial  and  the  other  at  an  angle  of  20  degrees  with  the 
radial  line.  After  being  milled  they  were  placed  on  another 
arbor,  which  was  a  neat  sliding  fit  in  them,  and  their  relative 
position  changed,  one  being  turned  half  way  around.  They  were 
then  clamped  together,  and  with  the  aid  of  a  knife-edged  straight- 
edge, their  accuracy  was  compared,  when  it  was  found  that  the 
slots  did  not  register  accurately.  The  high  surface  was  then 
carefully  scraped  down,  after  which  the  plates  were  changed 
around  to  a  different  position,  and  the  scraping  was  repeated, 
and  so  on  until  the  two  plates  could  be  placed  in  any  of  the  six 
positions  and  have  their  slots  in  perfect  alignment  with  one 
another.  This  method  gave  one  a  perfect  plate,  but  we  did  not 
like  the  making  of  two  plates  to  obtain  one,  or  the  hand-work 
that  was  involved. 

Our  next  plate  was  made  as  in  Fig.  38,  having  hardened, 
ground  and  lapped  tool-steel  pieces  a  inserted  and  held  in  position 
by  the  ^-inch  screws  b,  and  by  a  perfect  fit  in  the  slots,  which 
were  in  turn  milled  about  J  inch  deeper  than  the  slots  for  the 
index  finger  c.  One  side  of  these  lapped  pieces  stands  perfectly 
radial,  while  the  opposite  side  of  the  index  slot  is  at  an  angle  of 
20  degrees.  This  style  of  slot  assures  the  greatest  possible  ac- 
curacy, because  when  the  index  finger  enters  the  plate  the  radial 
side  of  the  slot  stands  perpendicular,  thus  not  easily  permitting 
any  chips  to  lie  on  it,  while  the  other  side,  being  at  an  angle,  has 
a  tendency  to  force  the  radial  side  tight  against  the  index  finger. 
Should  a  chip  get  between  the  angular  side  and  the  index  finger, 
it  would  not  impair  the  accuracy  of  the  divisions. 

The  method  employed  in  making  the  plate,  as  well  as  many 
others  with  different  numbers  of  slots,  has  proven  very  satis- 
factory. At  the  start  the  plate  was  milled  out  in  the  regular 
way  on  a  milling  machine,  using  the  dividing  head  to  space  the 


42  GAGES  AND  GAGING   SYSTEMS 

slots  as  accurately  as  possible.  At  this  same  setting  the  screw 
holes  were  drilled  and  counterbored  so  that  each  one  would  be 
in  perfect  relation  with  the  others.  The  plate  was  then  removed 
from  the  machine  to  await  the  finishing  cut  being  taken,  which 


FIG.  38.  —  Index  Plate. 

would  be  but  a  few  thousandths  from  each  side  of  the  slots  into 
which  the  hardened  plates  fit.  The  machine  was  then  prepared 
for  the  finishing  cut  as  in  Fig.  39.  A  dividing  head  was  selected 
of  which  the  worm  could  be  released  from  the  worm  wheel,  thus 
permitting  the  spindle  to  turn  independently.  Most  of  the  latest 


GAGES   AND   GAGING   SYSTEMS 


43 


u 


44  GAGES  AND  GAGING   SYSTEMS 

style  heads  are  constructed  in  this  way,  but  if  one  of  that  pattern 
is  not  at  hand,  a  regular  head  can  be  used  with  the  aid  of  the 
wooden  wedge  tapped  in  between  the  face-plate  and  platen  of 
the  machine  to  hold  it  in  position,  the  index  crank  being  used  to 
turn  the  spindle,  but  not  for  spacing  purposes.  A  large  face- 
plate was  placed  on  the  spindle  of  a  larger  diameter  than  the 
swing  of  the  dividing  head  would  admit,  thus  necessitating  the 
use  of  the  adapter  which  comes  with  every  milling  machine. 
Into  this  plate  six  holes  were  drilled,  the  spacing  being  done  with 
the  head  itself.  These  holes  were  then  tapped  out  to  fit  10-32 
screws,  which  in  turn  held  "buttons,"  care  being  taken  that  all 
buttons  were  accurately  to  one  diameter  (hardened,  ground,  and 
lapped  buttons  fitting  into  a  perfect  ring  gage  are  the  only  prac- 
tical ones  to  use).  These  buttons  will  be  seen  in  Fig.  39  marked 
a.  A  hardened  and  ground  arbor  b  was  then  placed  in  the  spindle 
of  the  head,  on  the  end  of  which  and  projecting  from  the  head  is 
lapped  stud  b,  of  the  same  diameter  as  the  buttons.  Another 
piece  d  is  held  securely  on  the  adapter  with  a  bolt,  and  in  turn 
carries  another  hardened  and  lapped  stud  c  fitted  to  it,  also  of  the 
same  diameter  as  the  buttons.  This  stud  c  is  the  stationary 
point  from  which  all  divisions  are  made. 

The  form  of  slot  shown  in  Fig.  38  has  another  advantage,  in 
that  the  wear  is  confined  almost  entirely  to  the  beveled  side  where 
it  does  not  impair  the  accuracy  of  the  work.  Moreover,  the 
accuracy  being  determined  entirely  by  the  radial  side,  the  pre- 
cision work  is  confined  to  that  side. 

TESTING  GAGE  FOR  INDEX  PLATES 

For  testing  up  index  plates  the  device  shown  in  Fig.  40  is  a 
very  simple  contrivance.  It  is  composed  of  a  cast-iron  plate 
with  a  central  locating  stud,  —  for  locating  and  swinging  the 
index  plate,  a  positive  stop,  —  adjustable,  a  and  the  indicator  b. 
The  manner  in  which  this  gage  is  used  is  self-evident. 

MAKING  ANOTHER  ACCURATE  INDEX  PLATE 

Piece  A,  Fig.  41,  we  would  grind  parallel  on  both  faces,  then 
grind  and  lap  the  hole  to  size,  and  work  from  the  hole  and  face  of 
the  index  plate.  This  would  detect  the  error  in  the  blocks  if  out 
of  parallel  with  the  hole. 


GAGES  AND  GAGING  SYSTEMS 


45 


Piece  A  is  mounted  on  stud  B,  which  is  a  good  fit  in  A.  The 
angle  iron  has  a  hole  for  a  loose  fit  for  the  end  of  stud  B,  which 
is  threaded  for  a  nut.  The  hole  under  block  d  allows  one  to  see 


FIG.  40.  —  Gage  for  Testing  Index  Plates. 

through  when  adjusting  the  blocks  at  right  angles;  piece  A  is 
clamped  to  the  angle  iron  with  a  strap  and  screw  that  enters  stud 
B;  angle  C  is  gray  iron  and  narrow  enough  to  allow  to  extend  out 
from  the  sides  to  the  ground. 


FIG.  41.  —  Making  an  Accurate  Index  Plate. 

Fig.  42  is  composed  of  a  gray  iron  block  D,  and  a  piece  of 
finished  flat  steel  E,  which  is  &  inch  thick  and  worked  out  to  the 
outline  of  piece  A,  Fig.  i,  leaving  plenty  of  space.  The  ends  are 
beveled,  hardened  and  ground  back  on  face  e  about  a  quarter 


GAGES   AND  GAGING   SYSTEMS 


of  an  inch.  In  lapping  this  edge,  make  it  rounding,  not  sharp. 
Block  D  is  finished  on  three  sides  of  the  sides;  top,  bottom,  and 
the  face  piece  E  is  attached  to.  This  allows  you  to  turn  it  over 
and  prove  both  sides  of  the  index  blocks.  The  dimension  x, 


FIG.  42.  —  Index  Plate  Practice. 

Figs.  41  and  42,  should  be  close  enough  to  allow  the  square  to 
be  used  either  side  up. 

Fig.  43  is  the  old  principle  of  the  reversible  parallel  for  testing 
a  square;  parallel  F  swings  on  stud  G,  and  is  adjusted  with  the 
screws  shown  at  the  top,  which  are  pivoted  to  swing  out  of  the 
way  to  allow  the  parallel  to  be  reversed  end  for  end.  To  test 


^7)^  -Pivot  Screw 


FIG.  43.  —  Index  Plate  Practice. 

the  square,  you  adjust  the  parallel  to  the  square  on  one  side;  let  the 
parallel  remain  in  this  position,  place  the  square  at  the  other 
side  of  the  parallel,  and  it  will  show  twice  the  error,  if  there  is 
any.  To  test  the  parallel,  reverse  it  end  for  end,  then  adjust  to 
the  square.  It  should  fit  the  square  on  both  sides  of  the  parallel, 
or  it  will  show  twice  the  error  on  one  side  if  not  parallel. 


GAGES  AND   GAGING   SYSTEMS  47 

With  the  index  plate  placed  in  position  on  the  angle  iron, 
Fig.  41,  blocks  a  and  b  are  leveled  up,  and  have  been  found  to 
have  the  least  amount  to  be  roughed  off;  these  are  ground  off; 
then  the  index  plate  is  revolved  a  quarter  turn  by  using  the 
square  in  Fig.  43  to  square  to  the  surface  just  ground,  and  c  and 
d  are  ground  to  the  same  reading  of  the  index  wheel  on  the  grinder 
or  to  a  hight  gage.  Now  revolve  the  index  plate  another  quarter 
turn,  using" the  square  again,  and  at  the  fourth  quarter  turn  you 
have  gone  around  all  faces  of  your  blocks.  Now  take  a  light  cut  to 
make  up  for  the  wear  on  the  wheel  from  the  roughing  cuts,  and 
go  around  without  disturbing  the  setting  of  the  wheel,  and  at 
the  third  quarter  turn  you  can  prove  your  square  and  setting 
with  a  micrometer.  Your  last  surface  should  be  parallel  with 
the  one  under  it.  After  going  around  the  second  time  your 
blocks  are  divided  equally  each  side  of  the  center,  but  are  too 
large.  You  have  found  approximately  how  much  your  wheel 
lost  in  size  by  the  roughing  cuts,  so  you  can  rough  them  down 
pretty  close  for  the  last  roughing  leaving  just  enough  to  finish 
with.  This  leaves  nothing  to  guess  at;  the  errors  can  be  located 
and  measured,  all  operations  are  tested  before  and  after  setting 
and  clamping.  The  square  is  used  on  the  index  plate  face  as 
well  as  on  the  side  of  the  blocks. 

If  we  find  that  clamping  in  the  way  described  distorted  the 
plate,  we  should  drill  a  hole  through  stud  B,  and  use  a  bolt  and 
nut  instead  of  a  cap  screw. 


SECTION    II 

ACCURATE  TEST  AND  INSPECTION  GAGES,  ELECTRIC 
AND  OTHER  MEASURING  MACHINES:  TOGETHER 
WITH  SPECIAL  INDICATORS  FOR  INSPECTING 
DUPLICATE  WORK. 

INSPECTION  GAGE  FOR  WALL  THICKNESS 

IN  Figs.  44  and  45  are  test  pieces  for  which  the  gages  shown 
in  Figs.  46,  47,  48  and  49  were  made.     These  tools  constitute  a 


FIG.  44. —  Work  to  be  Tested. 

set  of  test  and  inspection  gages  of  decidedly  interesting  design, 
possessing  adaptable  features  which  may  be  used  to  advantage 
in  similar  gages  for  verifying  measurements  of  small,  accurately 
machined  steel  parts.  All  four  of  the  gages  are  graduated  to 
indicate  variations  down  to  .0005  inch. 

The  work,  Figs.  44  and  45,  for  which  the  inspection  tools  were 
utilized,  consisted  of  two  parts  of  tool  steel,  which  were  machined 
to  extremely  accurate  dimensions  and  were  required  to  fit  or 
assemble  together  perfectly.  The  part  shown  in  Fig.  44,  as  may 
be  seen,  has  a  dovetailed  channel  milled  in  one  side  for  its  entire 
length,  and  has  the  web  punched  out  to  form  a  hole  at  E.  This 
part,  after  all  milling  operations  had  been  concluded,  was  hard- 
ened and  tempered;  the  temper  being  drawn  down  sufficiently  low 
to  allow  shaving  the  dovetailed  surfaces  to  finish  with  "Novo" 
steel  cutting  tools,  after  which  the  sides  and  edges  of  the  part 
were  ground  to  limit  sizes  with  a  cup-shaped  emery  wheel  in  a 

48 


GAGES  AND   GAGING   SYSTEMS  49 

specially  constructed  grinder.  It  was  after  this  operation  that 
the  two  gages  illustrated  in  Figs.  46  and  47,  were  used  to  deter- 
mine the  degree  of  interchangeability  attained  in  the  parts  through 
the  various  concluding  mechanical  operations. 


FIG.  45.  — Work  to  be  Tested. 

The  micrometer  gage  shown  in  Fig.  46  was  used  to  determine 
the  width  of  the  part  from  the  dovetail  to  the  edges,  or  the  wall, 
as  is  indicated  in  the  lower  view,  in  which  is  shown  a  cross-section 
of  the  work  in  position  on  the  dovetail  locating  piece  L.  After 


FIG.  46.  —  Micrometer  Test  Gage. 

gaging  one  side  in  the  manner  outlined,  the  other  side  is  inspected 
by  simply  reversing  the  work  on  the  dovetail  locator.  The  draw- 
ing of  the  gage  is  so  clear  and  self-explanatory  that  a  detailed 
description  of  construction  will  be  unnecessary.  F,  G,  H,  I,  and 
J  comprise  the  micrometer  portions,  L  is  the  locater,  M  is  the 


5° 


GAGES   AND   GAGING   SYSTEMS 


block  upon  which  it  is  formed,  N  the  fastening  screw  and  dowels 
which  fasten  and  locate  it  in  position  on  the  body  of  the  gage; 
P  is  the  base,  and  O  the  stem  of  the  gage.  Two  flathead  screws 
were  used  for  fastening  the  gage  to  the  work-bench.  All  locating 
and  test  parts  of  the  gage  were  hardened  and  carefully  ground 
and  lapped. 

TEST  GAGE  FOR  WIDTH  OF  DOVETAIL  CHANNEL 

The  micrometer  gage  illustrated  in    Fig.   47  was    used    for 
measuring  the  width  of  the  dovetail  channel  in  Fig.  44:  that  is, 


FIG.  47.  —  Micrometer  Test  Gage. 

the  distance  between  points  A  and  B.  This  gage  consists  of 
base  B,  which  is  fastened  to  the  work-bench  when  in  use,  stem  A, 
two  slides  T  T,  which  have  raised  angular-faced  projections, 
which  conform  to  the  angle  of  the  dovetail  in  the  work,  and  the 
micrometer  portions  S,  R  and  Q.  The  manner  in  which  the 
gage  is  used  to  determine  the  width  of  the  dovetail  is  clearly  in- 
dicated in  the  view  at  right  of  Fig.  47,  a  cross-section  of  the  work 
being  shown  in  position.  By  revolving  the  barrel,  by  means  of 
the  knurled  end  Q,  the  slide  T  at  the  right  moves  back  to  allow 
removing  or  locating  the  work;  while  the  revolving  of  the  barrel 
in  the  opposite  direction  causes  the  slide  T  to  move  out  and  ex- 
pand to  the  full  width  of  the  dovetail  channel  in  the  work.  The 


GAGES  AND  GAGING  SYSTEMS 


other  side,  T,  is  fixed.  A  light  spiral  spring,  which  is  shown  in 
the  plan  of  Fig.  47,  assists  the  slide  to  move  back  readily  when 
the  barrel  is  revolved  and  the  work  is  removed  or  located. 

It  will  be  noticed  that  both  gages  described  in  the  foregoing 
are  simple  in  design  and  of  comparatively  inexpensive  construc- 
tion, when  the  rapidity  with  which  the  work  may  be  handled  and 
inspected  in  them,  and  the  required  accuracy  of  the  tests,  are 
considered.  In  case  of  wear  in  any  of  the  precision  parts  of 
either  gage,  the  error  may  be  rectified  by  simply  making  suitable 
adjustments,  provision  for  which  may  be  seen  in  the  drawings; 
thus  no  difficulty  is  experienced  in  maintaining  the  accuracy  of 
the  tools. 


FIG.  48.  —  Test  Indicator. 

DECIMALLY  GRADUATED  GAGE  FOR  DOVETAIL  SLIDE  INSPECTION 

In  Fig.  45  is  shown  the  dovetail  slide  which  is  required  to 
assemble  on  the  part  shown  in  Fig.  44.  This  piece  is  also  made 
of  tool  steel,  is  accurately  machined  all  over,  is  shaved  on  the 
dovetail  surfaces,  A  and  B,  and  then  ground  on  the  back.  It 
was  for  verifying  the  interchangeability  of  this  part  that  the 
decimally  graduated  inspection  gages  shown  in  Figs.  48  and  49 
were  used  for  determining  the  exact  amount  of  variation  in  the 
parts  from  the  inner  edge  of  the  dovetail  A  and  B,  to  the  ground 
edges  of  the  body  portion  at  C  and  D. 

The  gage  consists  of  a  flat  cast-iron  base,  F,  cored  at  G  and 
equipped  with  four  steel  legs,  K  K  K  K.  W  W  is  the  test  and 


52  GAGES  AND  GAGING   SYSTEMS 

gage  portion,  and  consists  of  a  dovetail  piece  of  tool  steel  which 
is  fitted  and  gibbed  into  a  channel  in  F,  as  shown  by  gib  P  and 
screws  O  O.  This  piece  is  milled  away  in  the  center  so  as  to 
provide  a  clearance  for  the  pointer  /,  which  is  pivoted  on  a  small 
pin  at  N.  The  projecting  end  Q  of  W  is  hardened,  ground  and 
lapped  to  conform  to  the  angle  of  the  shaved  dovetail  surfaces 
of  piece,  Fig.  45;  it  is  also  drilled  longitudinally  in  the  center  to 
accommodate  the  plunger  R,  which  is  fitted  to  "float"  in  the 
reamed  hole.  The  rounded  end  of  R  at  5  rests  against  the  edge 
of  the  pointer.  Pin  T  in  the  end  of  the  plunger  prevents  it  from 
getting  away,  and  the  light  spring  M  serves  to  keep  the  plunger 
out  when  the  work  is  not  against  it.  Knurled  head  screw  U, 
spanned  by  yoke  V  and  screwed  into  F,  is  utilized  to  correct  any 
inaccuracies  in  the  precision  parts  which  occur  through  use  and 
wear.  The  graduations  for  reading  the  tests  are  at  /,  at  the 
extreme  end  of  F,  with  the  end  /  of  the  point  matching  them. 
When  the  pointer  registers  at  o,  the  work  is  up  to  the  require- 
ments; if  it  points  at  T  at  the  left,  the  work  is  considerably  too 
large;  if  it  points  at  5  on  the  right,  the  work  is  .0025  too  small. 

In  using  the  gage  it  is  placed  on  the  bench  before  the  inspector 
and  the  dovetail  slide,  Fig.  45,  is  located  on  it,  with  one  dovetail 
edge  resting  against  the  angular  face  of  Q,  and  the  edge  D  resting 
against  plunger  R;  thus,  upon  the  inspector  pressing  down  and 
in  upon  the  work  the  edge  forces  the  plunger  R  inward,  and 
therefore  causes  the  pointer  to  register  the  reading  at  /.  A 
spanner  of  small  diameter  drill  rod  at  H  H  acts  as  a  guard  for  the 
pointer. 

DECIMALLY  GRADUATED  SLIDE  GAGE  FOR  DOVETAIL  INSPECTION 

In  Fig.  49  we  have  another  decimally  graduated  test  gage, 
used  in  the  inspection  of  part  Fig.  45.  It  is  used  to  determine 
the  exact  width  of  the  dovetail  portion,  from  A  to  B.  A  base 
of  cast-iron  is  machined  to  accommodate  the  hardened  and  ground 
angular-faced  pieces  /  and  F.  Piece  /  is  fastened  and  located  by 
screws  K  K  and  /  /,  while  piece  F  is  left  free  to  slide  in  the  holder. 
It  will  be  noticed  in  the  plan  view  of  this  gage  that  the  dovetail 
edges  G  and  H  of  I  and  E,  respectively,  are  at  an  angle  of  a  few 
degrees  with  the  dovetailed  channel  in  the  base;  thus  as  the 
slide  F  is  pushed  forward  the  space  between  G  and  H  decreases ; 


GAGES   AND  GAGING   SYSTEMS 


53 


and  as  it  is  pulled  back  in  the  opposite  direction  the  space  in- 
creases; therefore  by  simply  entering  the  work  so  that  the  dove- 
tail part  rests  between  G  and  H,  and  then  pushing  the  slide 
forward  until  the  work  is  clamped  or  held  tightly,  a  reading  may 
be  instantly  made  by  noting  the  relation  of  the  graduated  lines 
with  zero  point  0  at  P. 

Although  gages  of  the  type  described  in  the  foregoing  may 
appear  quite  simple  and  easy  to  construct,  considerable  skill  and 
care  are  necessary  in  the  grinding,  lapping  and  graduating,  in 
order  to  produce  reliable  precision  instruments  for  the  inspection 
of  accurate  work. 


J; 


?0  ir 

.•)_ 


i  _ 

1 

fr 


K 

H     G 

4N  i 

//   \\\ 

-3  f 

F                \ 

E                j 

i   ~J~» 

FIG.  49.  —  Graduated  Slide  Test  Gage. 

LARGE  MICROMETER  TEST  CALIPER  FOR  MARINE  ENGINE  LINERS 

The  gage  illustrated  in  Fig.  50  was  used  for  gaging  sixteen 
liners  for  four  marine  engines.  The  outside  diameters  of  the 
liners  —  40,  56,  77  and  108  inches — were  turned  for  a  press  fit 
in  the  cylinders.  There  were,  of  course,  four  gages  made,  all  like 


54 


GAGES  AND  GAGING   SYSTEMS 


the  drawing.  The  size  was  taken  from  the  cylinders  with  the 
ordinary  gage  made  of  a  stick  of  wood  with  wood-screws  in  each 
end  for  adjustment.  The  gage  in  the  drawing  was  then  set  for 
the  outside  diameter  from  the  gage,  enough  larger  to  make  a 
good  press  fit.  As  one  can  see  from  the  drawing,  the  gages  were 
made  of  ordinary  iron  pipe  and  fitting,  and  they  cost  but  little. 
The  top  clamp  of  each  gage  was  extended  out  and  a  hole  was 
drilled  through  for  a  hook.  From  a  column  near  the  front  of  the 
lathe  a  rope  was  run  up  to  a  wooden  bracket,  the  end  of  the 
bracket  running  out  to  the  center  of  the  lathe.  The  rope  was 


Section  on  A-B 

FIG.  50.  —  Gage  for  Marine  Engine  Liners. 

run  out  to  the  end  of  the  bracket  and  then  down  to  the  lathe 
with  a  hook  on  the  end,  which  went  through  the  eye  in  the  top 
of  the  gage.  The  gage  was  then  hoisted  up  until  the  adjustable 
screws  were  in  line  with  the  center  of  the  lathe,  and  then  fastened, 
so  that  to  try  the  gage  over  the  liner  for  size,  a  helper  held  one 
point  on  the  line  on  one  side,  while  the  machinist  raised  and  low- 
ered the  gage  on  the  other  side. 

A  TEST  GAGE  FOR  LARGE  DUPLICATE  ROLLERS 

The  gage  shown  in  Figs.  51  and  52  was  used  on  a  lot  of  cast- 
steel  rollers  for  battleship  turrets  of  the  "  Kearsarge"  type.  The 
rollers  were  to  go  between  two  tracks  on  which  the  turrets  re- 
volve, and  had  to  be  as  near  alike  as  they  could  be  made,  so  the 


GAGES  AND  GAGING  SYSTEMS 


55 


weight  of  the  turret  and  guns  would  be  evenly  distributed.  Tap- 
bolts,  shown  in  the  end  view  Fig.  52,  hold  the  V-blocks  in  place. 
They  were  put  in  before  the  V-blocks  were  planed,  and  then  the 
surface  plate,  with  V-blocks  in  place,  was  put  on  the  planer  and 


FIG.  51.  —  Test  Gage  for  Duplicate  Rollers. 

set  so  that  one  V-block  would  be  planed  deeper  than  the  other, 
and  thus  bring  the  bottom  side  of  the  taper  roller  parallel  with 
the  surface  plate.  The  roller  was  set  in  the  V-blocks,  so  the 


FIG.  52.  —  Test  Gage  for  Duplicate  Rollers. 

distance  between  the  inside  of  the  flange  of  the  roller  and  V- 
blocks  at  the  bottom  was  equal  at  each  end.  The  V-shaped 
piece  E  on  the  top  of  the  roller  was  planed  on  the  V-side  to  fit 
the  taper  of  the  roller.  It  was  then  placed  on  the  sample  roller, 
which  was  set  in  the  V-blocks  already  planed,  and  the  top  edge 
of  the  V-piece  was  laid  off  with  a  surface  gage  and  planed  and 


GAGES   AND   GAGING   SYSTEMS 


then  scraped,  the  distance  between  the  flanges  of  the  roller  and 
the  ends  of  V-piece  being  kept  equal.  After  the  rollers  were 
turned  to  size  they  were  placed  on  the  V-blocks,  the  block  under 
the  small  end  of  the  roller  being  one  half  the  taper  higher,  so 
that  the  bottom  of  the  roller  would  be  parallel  with  the  surface 
plate.  Plate  E  was  then  placed  on  the  roller  and  the  gage  F 


FIG.  53.  —  Simple  Shop  Gages. 

moved  along  the  edge  of  E.     If  there  was  any  variation  in  hight 
or  in  taper  it  would  soon  show  it. 

A  SET  OF  SIMPLE  SHOP  GAGES 

The  illustration,  Fig.  53,  shows  a  plan  adopted  to  provide  an 
equipment  of  gages  for  end  measurement.  Outside  gages  A 
were  made  in  exact  inches  between  the  shoulders  a  a,  and  the 


t 


FIG.  54.  —  Keyseat  Gage. 

blocks  B,  of  which  there  were  two  sets  made,  included  sizes  from 
J  to  i  |f  inch  by  thousandths,  and  one  iTV~inch  block.  The 
latter  was  used  in  place  of  a  tV-inch  block,  which  would  have  been 
too  thin  to  hold  with  the  clamp  as  made.  Male  gages  to  cor- 
respond were  made  of  square  steel  and  ground  to  length  after 
hardening.  By  this  method  a  large  range  of  accurate  gages  was 
available  at  a  comparatively  small  cost. 


GAGES  AND   GAGING   SYSTEMS 


57 


GAGES  FOR  LOCATING  KEYSEATS 

Figs.  54  and  55  and  56  show  side  and  end  views  of  scratch 
gages  for  scratching  lines  on  chalked  surfaces  of  the  spindles 
before  they  are  placed  in  the  fixture,  for  locating  the  positions  of 
keyseats  in  relation  to  the  shoulders,  it  being  found  that  when 
operators  worked  from  drawings  it  was  almost  impossible  to 
obtain  uniform  results. 

The  gages  consist  simply  of  light  bars  with  hardened  scratch- 
pins  or  points  inserted  at  the  proper  distances  from  the  ends, 


J 


FIG.  55.  —  Key  seat  Gage. 


and  each  gage  is  lettered  to  indicate  the  particular  size  of  spindle 
for  which  it  is  to  be  used. 

Correct  depth  of  keyways  is  obtained  by  making  use  of  the 
graduated  dial  of  the  elevating  screw  of  the  milling  machine. 


FIG.  56.  —  Keyseat  Gage. 

A  NEW  SYSTEM  OF  GAGES  FOR  THE  PLANER 

We  present  in  Figs.  57,  58  and  59  a  gaging  appliance  as 
used  by  the  Bullard  Machine  Tool  Co.,  Bridgeport,  Conn.  It  is 
certainly  unusual  as  well  as  highly  meritorious. 

The  gage  is  intended  for  the  three  slots  of  boring  machine 
tables,  in  which  chuck  jaws  are  inserted.  For  reasons  of  inter- 
changeability  as  well  as  economy  of  production,  it  is  obviously 
desirable  that  these  slots  be  uniform,  and  this  the  device  secures 
with  a  minimum  of  labor. 

The  boring  mill  tables  to  be  slotted  come  to  the  planer  with 
the  lathe  work  completed,  and  with  a  concentric  hole  through  the 
center  which  enables  them  to  be  mounted  upon  a  post  having  a 
tongue  fitted  to  the  planer  table  slot  in  such  a  manner  that  the 


GAGES  AND  GAGING   SYSTEMS 


FIG.  57. —  Planer  Gage. 

work  shall  be  in  line  with  the  slot.  On  the  front  end  of  the  planer 
table  is  bolted  the  bracket  casting  shown  in  the  figures.  This 
casting  has  a  tongue  at  a,  Fig.  57,  fitting  into  the  planer  slot.  The 
initial  or  plug  gage  for  the  chuck  jaw  groove  is  seen  at  b,  Figs. 
57  and  59,  where  its  shape  will  be  seen  to  be  that  of  the  groove 
to  be  made.  It  has  a  tongue  c  fitting  into  a  corresponding  groove 
in  the  bracket  casting  and  is  held  in  position  by  the  knurled 
headed  bolt  d.  The  bracket  is  composed  of  two  pieces  arranged 


GAGES  AND  GAGING  SYSTEMS 


59 


;;© 


FIG.  58.  — Planer  Gage. 

to  slide  vertically  upon  one  another  at  e,  Fig.  58,  whereby  the 
vertical  adjustment  of  the  gage  as  a  whole  is  accomplished.  The 
gage  is  surrounded  by  a  series  of  beveled  plungers  /,  one  of  these 
plungers  being  provided  for  each  face  of  the  plug  gage  which  is 
reproduced  in  the  boring  machine  table.  The  construction  of 
these  plungers  is  shown  in  Fig.  58,  where  they  will  be  seen  to  have 
a  tail  g,  sliding  through  a  threaded  bush  b,  while  a  coiled  spring 
i  forces  the  plug  toward  the  gage  a.  It  will  be  seen  that  with 


6o 


GAGES  AND  GAGING   SYSTEMS 


the  gage  a  inserted  in  the  fixture  the  spring  will  force  the  various 
plugs  to  contact  with  the  gage,  and  in  this  condition  the  bushes 
h  are  carefully  adjusted  until  the  tails  g  are  exactly  flush  with 
them.  The  ends  of  the  tails  and  bushes  are  carefully  hardened 
and  ground,  and  of  course  by  applying  the  end  of  the  finger  to 
them  the  adjustment  can  be  determined  with  a  good  deal  of 
accuracy.  A  thousandth  of  an  inch  can  easily  be  split  into 
several  pieces  by  this  method. 

With  this  adjustment  made,  the  plug  gage  a  is  removed  and 
the  tool  is  inserted  in  the  planer.  When  brought  opposite  the 
different  plungers,  the  tools  are  adjusted  until  they  press  the 


Q 


0) 


LLU 

FIG.  59.  —  Planer  Gage. 


plungers  back  to  such  a  point  that  the  tails  g  and  bushes  h  are 
again  truly  flush,  when  the  tool  obviously  occupies  the  same 
position  as  the  corresponding  face  of  the  original  plug  gage,  and 
is  correctly  set  for  the  finishing  cut  of  the  corresponding  face  of 
the  slot  to  be  made. 

Connected  with  each  plunger  will  be  seen  a  ball-handled  pin  j 
projecting  through  a  cam-shaped  slot  in  the  main  casting.  These 
pins  enable  the  operator  to  draw  the  plungers  back,  and  also  to 
facilitate  the  placing  of  the  plug  gage  in  the  fixture. 

It  will  be  observed  that  the  fixture  described  not  only  sizes 
the  slot,  but  positively  positions  it  as  well,  and  it  would  seem  to 
be  applicable  to  a  considerable  variety  of  duplicate  work  done  on 
the  planer. 


GAGES  AND  GAGING   SYSTEMS  61 

THE  TESTING  AND  COMPARISON  OF  END  STANDARDS  OF  LENGTH 

End  standards  of  length,  called  gages,  are  tested  and  com- 
pared with  one  another  by  means  of  measuring  machines,  made 
by  many  engineering  firms  both  in  the  United  States  and  Europe. 
These  machines  are  identical  in  principle,  and  differ  little  in 
form  from  the  original  one  invented  by  Sir  Joseph  Whitworth. 
Their  principle  is  that  the  gage  rests  against  one  jaw,  fixed,  of  the 
machine,  while  the  other  jaw  is  moved  forward  by  a  micrometer 
screw  until  it  touches  the  gage.  Compression,  more  or  less,  of 
machine  and  gage,  is  required  before  any  indication  can  be 
obtained  that  both  jaws  are  firmly  in  contact  with  the  gage. 
These  machines  will  in  the  future  be  spoken  of  as  mechanical 
touch  machines,  as  distinguished  from  the  new  machines  called 
electric-touch  machines.  In  practice  it  has  been  found  desirable 
to  introduce  some  index  of  the  touching,  e.g.,  a  gravity-feeler, 
spirit-level,  or  the  raising  of  liquid  in  a  fine  tube. 

The  weight  of  the  gage,  often  large,  should  never  —  as  is 
sometimes  done  —  be  supported  by  the  grip  of  the  two  jaws;  for 
then  there  is  considerable  end-thrust  of  the  jaws,  with  consequent 
longitudinal  strain  in  the  machine,  in  addition  to  the  vertical 
strain  due  to  the  weight  of  the  gage.  If  the  whole  or  part  of  the 
weight  of  the  gage  be  supported  by  the  jaws,  though  the  latter 
be  parallel  to  one  another  initially,  they  will  not  be  so  after  being 
weighed.  The  errors  which  enter  into  the  measurements  made 
by  these  machines  differ  in  kind  and  degree  according  to  the 
nature  of  the  gage.  There  are  three  kinds  of  gage. 


BAR  GAGES  WITH  PLAIN  PARALLEL  ENDS 

Each  jaw  has  a  flat  face,  and  each  end  of  the  gage  has  a  flat 
face.  Each  of  the  four  faces  has  defects  in  planeness  and  in 
being  not  strictly  parallel  to  the  other  three.  If  in  addition  a 
gravity-feeler  be  used,  it  introduces  extra  errors.  To  admit  so 
many  errors  of  unknown  amount  in  the  measurement  of  gages 
may  be  permissible  in  present-day  engineering  practice,  but  it 
does  not  satisfy  the  demands  of  exact  measurement.  Thus  to 
obtain  accuracy,  surface  contact  should  be  abandoned  and  point 
contact  used,  and  these  gages  should  be  measured  between  two 
rounded  points  or  spheres,  in  which  case  no  assumptions  are 


62  GAGES   AND  GAGING   SYSTEMS 

made  as  to  the  perfectness  or  parallelism  of  the  surfaces  involved. 
For  each  point  contact  we  require  a  more  delicate  means  of  per- 
ceiving contact  than  the  mechanical  one;  hence  the  electric- 
touch  method  is  employed.  It  has  been  developed  by  P.  E. 
Shaw,  of  England,  in  a  series  of  researches  since  1900. 

CYLINDRICAL  GAGES 

The  flat  faces  of  the  jaws  touch  the  cylinder  with  two  line 
contacts  at  opposite  ends  of  the  diameter  of  the  cylinder.  Non- 
planeness  and  non-parallelism  of  the  jaw-faces,  as  also  imper- 
fections in  the  cylinder,  introduce  errors,  though  these  are  less 
serious  than  for  Bar  gages.  Thus  for  accuracy  line  contact  should 
be  superseded  by  point  contact,  the  measurement  to  be  made 
between  lines  or  edges  on  the  jaws,  the  lines  being  not  parallel 
with  the  axis  of  the  cylinder. 

SPHERE  OR  BAR  WITH  SPHERICAL  ENDS 

The  face  of  each  jaw  touches  the  sphere  at  a  point.  Since 
the  jaw  faces  are  imperfect,  error  can  only  be  avoided  by  providing 
that  the  contact  of  the  two  faces  with  the  sphere  always  occurs  at 
the  same  places.  Thus,  for  accuracy,  contact  may  be  made  as 
usual  between  the  flat  faces  of  the  jaws,  if  the  surface  be  made 
true  and  contact  be  always  at  the  same  points  on  the  flat  faces. 

From  these  remarks  it  appears  that  for  each  kind  of  gage, 
measurement  should  be  made  by  point  contact,  the  jaws  to  sup- 
port no  part  of  the  weight  of  the  gage,  and  the  end  thrust  on  them 
to  be  reduced  as  much  as  possible.  The  method  described  below 
fulfils  these  conditions,  and  has  in  addition  the  advantage  of 
being  more  sensitive  than  the  old  method. 

DESCRIPTION  OF  MEASURING  MACHINE 

The  latest  form  of  the  machine  is  shown  in  Figs.  60,  61,  and 
62.  In  general  appearance  it  is  somewhat  like  the  usual  me- 
chanical touch  machines  mentioned  in  the  foregoing. 

There  are  two  headstocks  and  a  table  in  the  center,  all  resting 
on  a  massive  cast-iron  bed.  The  headstocks  each  carry  microm- 
eter screws  and  nuts  with  graduated  heads,  and  these  measure 
the  gage,  which  rests  on  and  is  clamped  to  the  table.  The  gage 


GAGES   AND   GAGING   SYSTEMS  63 

being  clamped  to  the  table  is  set  true  with  respect  to  the  axes  of 
the  micrometer  screws,  by  adjustments  of  the  table.  The  left 
screw  point  is  brought  into  electric  contact  with  the  gage;  then 
the  right  screw  point  is  brought  into  electric  contact  with  the 


PJLUJLUOJLOJUULULUL^^ 

FIG.  60.  —  Measuring  Machine. 


gage,  and  when  the  current  passes  through  the  gage  from  one 
measuring  point  to  the  other,  the  two  dividing  heads  are  read. 
To  turn  the  graduated  heads  the  screw  system  is  not  actually 


FIG.  61.  —  Measuring  Machine. 

touched  by  hand,  but  is  worked  by  a  hand-pulley  and  string,  the 
former  being  attached  to  the  base  of  the  headstock,  there  being 
a  large  pulley  on  and  concentric  with  the  head.  The  left  head- 
stock  is  a  replica  of  the  right  headstock;  to  save  space,  only  the 
measuring  point  of  the  left  headstock  is  shown.  Gage  d  rests 


64  GAGES  AND  GAGING   SYSTEMS 

on  the  table  /  and  is  clamped  to  it.  The  table  top  can  be  brought 
into  any  desired  plane  by  two  rotations,  as  follows: 

The  table  is  fitted  with  five  adjustments,  being  movable 
through  a  small  angle  about  a  horizontal  axis,  and  also  through  a 
small  angle  about  a  vertical  axis,  as  well  as  adjustable  in  hight. 
It  can  further  be  traversed  either  along  or  across  the  bed. 

In  Figs.  60  and  61  is  shown  a  nut  N  working  in  bearings  Elf 
E2,  and  having  the  screw  Sl  in  it.  A  steel  cone  n  is  screwed  into 
the  right  end  of  the  nut  N,  and  bears  against  the  stop  m.  There 
is  a  helical  spring  F  which  presses  forward  against  the  bearing 
Elt  and  back  against  the  nut,  forcing  the  cone  n  against  stop  m. 


FIG.  62.  —  Measuring  Machine. 


The  point  of  n  lies  truly  in  the  axis  of  nut  N,  and  the  front  face  of 
m  is  ground  truly  plane,  and  by  a  special  device  is  made  accurately 
normal  to  the  axis  of  the  nut  N.  By  this  means,  when  the  nut 
is  turned  it  should  be  a  true  rotational  motion,  without  any 
periodic  to-and-fro  translations  along  its  axis,  such  as  occur 
with  the  usual  coned  or  flat  bearings.  Subsequent  calibration 
of  the  screw  shows  how  nearly  this  ideal  has  been  approached. 
Fixed  to  the  nut  N  is  a  graduated  wheel  Q,  and  a  double  vernier 
g  is  shown  attached  to  the  casting  R.  The  wheel  is  centered  true 
with  the  nut  axis  by  means  of  the  double  vernier  in  the  usual 
way.  The  casting  R  has  a -front  part  T,  to  which  an  upright 
plate  U  is  screwed.  This  plate  carried  the  bearing  E,  the  bracket 
V  on  which  runs  the  yoke  a  and  pulleys  rlf  r2,  Fig.  62. 


GAGES   AND  GAGING   SYSTEMS  65 

The  screw  Sl  would  rotate  with  the  nut  if  free,  but  as  the 
yoke  q  which  runs  on  the  bracket  V  is  clamped  to  the  screw,  the 
latter  acquires  a  simple  translatory  movement  along  its  axis,  in 
or  out  of  the  nut,  according  as  the  latter  rotates  right-or  left- 
handedly.  The  screw  spindle  carries  an  index  mark  by  which 
the  position  of  the  screw  in  the  nut  can  be  seen  on  the  fixed  scale 
S,  Fig.  62. 

In  this  micrometer  system  of  rotating  nut  and  translating 
screw,  it  is  essential  for  accuracy  that  the  nut  have  no  transla- 
tion and  that  the  screw  have  no  rotation.  The  former  condition 
should  be  achieved  by  the  cone  end  method  of  working;  the 
latter,  by  making  the  yoke  and  bracket  rigid  and  insuring  by  a 
weight  that  the  former  presses  the  latter  with  constant  force. 
Backlash  and  looseness  between  micrometer  screw  and  nut  are 
minimized  by  the  pull  of  weights  ^  and  ^,  Fig.  62,  from  which 
pulley  strings  pass  over  pulleys  r±  and  r2  to  the  yoke  ends.  By 
this  means  the  screw  is  pulled  back  into  the  nut  by  a  steady  force. 

The  casting  R  is  electrically  insulated  from  the  plate  W  by 
a  mica  sheet,  and  by  having  the  screws  which  bind  R  and  W 
bushed  with  ebonite.  The  base  of  plate  W  is  grooved  to  fit  the 
part  X  of  the  bed,  and  presses  that  part  by  four  studs;  one  other 
stud  presses  on  the  flat  part  Y,  Fig.  62.  Thus  the  headstock 
rests  firmly  on  the  bed  at  five  points  of  support,  and  has  only 
one  degree  of  freedom  —  along  the  length  of  the  bed.  Fixed  on 
the  side  of  W  is  shown  a  bar  V,  on  which  the  hand-pulley  Z  can 
be  pulled  forward  and  clamped,  so  as  to  take  up  slack  in  the 
pulley  cord. 

The  two  micrometer  screws  and  nuts  were  cut  and  ground 
with  great  care  on  the  most  advanced  plan,  and  when  examined 
under  the  microscope  the  screws  appeared  highly  polished  and 
regular.  The  calibration  described  below  shows  that  there  is  a 
small  periodic  movement  at  each  rotation  of  the  nut,  probably 
due  to  its  bearings  being  eccentric  with  respect  to  its  axis.  But 
this  movement  is  perpendicular  to  the  line  of  measurement,  and 
the  resultant  errors  in  the  micrometry  are  of  a  lower  order  and 
probably  negligible. 

The  screw  heads  are  about  2  inches,  and  the  nuts  about  4 
inches  long,  so  that  the  screws  do  not  leave  the  massive  nuts  at 
any  point  in  the  run.  Steadiness  in  temperature  of  the  screw 
is  thus  obtained.  The  screw  diameter  is  i  centimeter,  the  pitch 


66  GAGES  AND  GAGING   SYSTEMS 

J  millimeter,  the  graduated  head  has  500  divisions,  and  the 
vernier  reads  tenths;  so  one  vernier  division  corresponds  to 
Ttf,£tfiF  millimeter  (or  approximately  .0000039)  in  the  micrometry. 
The  bed  is  5  feet  long  and  weight  200  pounds;  it  rests  on  three 
studs,  two  i  foot  apart  under  one  neutral  line,  and  one  under 
the  other  neutral  line.  A  voltaic  circuit,  consisting  of  a  cell  Clt 
a  resistance  box  Rlt  switch  X,  and  a  telephone  7\,  are  joined  to  a 
binding-screw  /x  on  the  bed,  and  to  another  binding-screw  12,  on 
each  headstock.  The  switch  is  put  to  right  or  left,  according 
as  one  wishes  to  make  contact  between  the  gage  and  the  left 
screw,  or  between  the  gage  and  the  right  screw. 

The  micrometer  microscope  Ml  rigidly  mounted  on  the  right 
headstock,  Fig.'6i,  is  used  for  reading  the  standard  invar  scale 
S3.  By  this  means,  as  in  the  Pratt  &  Whitney  measuring  machine, 
the  end  standards  may  be  compared  with  line  standards  of  length. 

MATERIALS  USED  IN  MACHINE 

The  bed  is  of  cast-iron.  Most  of  each  headstock  is  of  cast- 
iron,  in  one  piece,  but  the  front  plates  and  brackets  and  the 
base-plates  of  the  headstocks  and  table  are  of  wrought  iron. 
Brass  is  used  for  the  nut  bearings  and  for  most  of  the  table.  The 
micrometer  screws  are  of  silver  steel,  and  the  micrometer  nuts 
of  bell  metal,  which  is  very  hard.  The  part  of  the  screw  spindle 
projecting  from  the  front  of  the  nut  is  of  first-grade  invar.  All 
caps  and  fittings  on  the  screw  end  are  also  of  invar.  Since  invar 
cannot  be  ground  very  true,  the  faces  of  the  cups  are  of  thin  steel. 
The  idea  is  that  these  projecting  parts,  being  of  small  dimensions 
and  necessarily  uncovered,  are  more  liable  to  temperature  changes. 
The  consequent  errors  in  micrometry  are  small  since  the  expan- 
sibility of  invar  is  so  minute.  The  terminal  points  of  the  screw 
spindle  are  beads  of  iridio-platinum,  which,  being  hand-made 
and  non-oxidizable,  is  the  best  substance  for  electric-contact 
work.  The  beads  are  continuous,  with  a  short  piece  of  iridio- 
platinum  wire  which  was  hammered  into  the  hole  drilled  in  the 
end  of  the  invar. 

MEASURING  BAR  GAGES  WITH  FLAT  ENDS 

These  are  measured  in  the  electric-contact  measuring  machine 
between  two  points.  The  gage  is  put  on  the  table  and  clamped. 


GAGES  AND  GAGING  SYSTEMS 


It  must  first  be  set  so  as  to  have  one  face  normal  to  a  screw  axis 
by  adjusting  the  table. 

As  will  be  seen  from  the  contour  curves,  Figs.  63,  64,  65,  66, 
the  flat  ends  are  never  true  planes,  but  for  the  above  purpose  the 
gage  is  taken  to  be  set  when  the  contact  readings  on  all  points  on 
a  circle  near  the  edge  of  the  face  are  identical. 


Set 


Sot 


FIGS.  63  and  64.  —  Contour  Curves  of  Gages. 


The  flat  faces  are  roughly  6  millimeters  across;  the  left  screw 
point  is  brought  into  electric  touch  with  the  gage  at  the  center 
of  the  left  face,  marked  /  in  column  A,  Tables  i  and  2.  The 
right  screw  point  is  then  brought  up  to  touch  the  right  face,  the 
circuit  being  now  arranged  to  pass  from  the  left  screw  through  the 


Set 


Set 


FIGS.  65  and  66.  —  Contour  Curves  of  Gages. 


gage  to  the  right  screw.  The  two  micrometers  are  read  as  in 
columns  B  and  C.  Then  the  table,  and  the  gage  with  it,  are 
moved  i  millimeter  to  the  left;  the  contact  is  now  made  at  the 
place  2  in  column  A.  The  micrometer  head  readings  are  taken 
and  entered  in  columns  B  and  C,  as  before.  The  whole  face, 
except  near  the  edge,  is  thus  tested  in  thirteen  symmetrical 
places. 


68  GAGES  AND  GAGING   SYSTEMS 

Results  follow  for  two  new  gages,  made  by  the  best  firms,  in 
Tables  i  and  2.  The  numbers  in  columns  B  and  C,  and  in  other 
tables  below,  are  those  read  on  the  micrometer  heads,  so  that 
they  give  only  comparative  values  from  place  to  place,  and  would 
have  to  be  changed  alike  to  represent  absolute  values  of  the 
length  of  the  gages.  Column  D  is  the  sum  of  columns  B  and  C; 
the  larger  the  sum  the  less  the  thickness  of  the  gage  on  the  line 
in  question.  The  small  disagreement  between  the  results  for  the 
two  sets  is  shown  in  column  A.  The  gage  is  well  covered  through- 
out the  readings.  For  the  25-millimeter  gage,  Table  i,  the  errors 
arising  for  any  one  position  lie  between  o  and  0.4^1. l  These 
errors  can  be  attributed  mostly  to  bad  polish  of  the  surfaces. 
Grooves  are  visible,  and  small  changes  in  setting  the  surfaces 
would  bring  the  measuring  point  now  over  a  ridge,  now  over  a 
hollow. 

The  errors  in  reading  the  micrometer  can  be  ignored,  for  if 
any  observation  be  repeated  before  the  gage  is  moved,  the  differ- 
ence in  the  reading  never  amounts  to  more  than  o. I/A,  generally 
less.  Thermal  expansion  may  produce  a  small  deformation, 
since  about  three  quarters  of  an  hour  elapses  between  a  reading 
in  Set  I  and  the  corresponding  one  in  Set  II.  (See  Tables,  pp. 

69  and  70.) 

The  difference  in  the  gage  thickness  in  different  places  amounts 
to  3-6/x.  To  show  the  nature  of  the  gage,  contour  figures  are 
drawn,  one  for  each  set.  These  curves  are  not  contours  for  one 
surface  in  the  usual  way,  but  represent  the  joint  effect  of  the  two 
end  faces  of  the  gage. 

In  the  1 5o-millimeter  gage  differences  are  slightly  more, - 
o.i/u,  to  0.5/u.  (thermal  expansion  exercises  more  influence  for  long 
gages)  than  for  the  25-millimeter  gage.  But  the  difference  in 
the  gage  thickness  from  place  to  place  amounts  to  5.8^1.  The 
contour  figures  are  given.  The  faces  are  not  normal  to  the  length 
of  the  gage,  and  no  reading  can  be  taken  at  places  5  and  9;  when 
in  these  positions  one  screw  end  touches  the  gage,  the  other  screw 
end  does  not  make  contact  on  the  other  face,  but,  if  continued, 
would  meet  the  gage  on  its  side.  The  actual  length  of  this  gage 
was  found  to  be,  at  18.5  deg.  C,  1 50.0332  millimeters,  and  1 50.0325 
millimeters  in  two  distinct  evaluations,  taken  at  place  i,  Table  2. 

1  Micron,  the  millionth  part  of  a  meter,  or  j-g^  of  an   English  inch,  repre- 
sented by  the  Greek  letter  /*. 


GAGES   AND  GAGING   SYSTEMS 
TABLE    i.  — 25-MILLIMETER   GAGE 


69 


SET  I 

SET  II 

A 

D  = 

, 
— 

D'-o 

B 

c 

Br 

C' 

B  +  C 

B'-C' 

i 

116.5 

147-9 

264.4 

117.6 

146.9 

264.5 

+   O.I 

2 

"7-5 

146.3 

263.8 

117.4 

146.7 

264.1 

+  0.3 

3 

U7-3 

146.9 

264.2 

118.2 

146.3 

264.5 

+  0.3 

4 

117.9 

I477 

265.6 

118.7 

146.9 

265.6 

0.0 

5 

117. 

149-9 

266.9 

118. 

148.9 

266.9 

0.0 

6 

117. 

147.4 

264.4 

"7-5 

147.1 

264.6 

+   0.2 

7 

117.8 

147.6 

265.4 

118.4 

J47-3 

265.7 

+   0.2 

8 

116.6 

147-5 

264.1 

117.9 

146.6 

264.5 

+  0.4 

9 

118. 

147-5 

265-5 

118.1 

147-7 

265.8 

+  0.3 

10 

118. 

147-5 

265.5 

117.7 

147.9 

265.6 

+   O.I 

ii 

117.7 

146. 

263.7 

117.3 

146.6 

263.9 

4-   0.2 

12 

118.9 

148.5 

267.4 

II9-5 

147.9 

267.4 

0.0 

13 

119. 

147-5 

266.5 

119.6 

147.1 

266.7 

+   0.2 

TABLE   2.—  iso-MILLIMETER   GAGE 
THE  UNITS  ARE  MICRONS 

i 

395- 

96.2 

491.2 

395- 

96. 

491. 

—  O.2 

2 

397- 

93-8 

490.8 

396. 

94-5 

49°-  5 

-  °-3 

3 

396. 

94.9 

490.9 

395- 

95-5 

490-5 

-  0.4 

4 

398.7 

93-5 

492.2 

398. 

93-9 

491.9 

-  °-3 

5 

6 

394- 

98.7 

492.7 

396. 

96.6 

492.6 

—   O.I 

7 

396. 

95-5 

49  1  -5 

396- 

95  -° 

491. 

~  0.5 

8 

398.3 

96.7 

495- 

399- 

95-5 

494-5 

-  o-5 

9 

10 

396. 

93-7 

489-7 

396. 

93-4 

489-4 

-  o-3 

ii 

397- 

93-4 

490.4 

397-5 

92.8 

49°>3 

—  o.i 

12 

398. 

91.7 

489.7 

399- 

90.5 

489.5 

—   O  .2 

13 

396- 

92.9 

488.9 

396. 

92.7 

488.7 

—   0.2 

70 


GAGES   AND   GAGING   SYSTEMS 


TABLE   3. —  THREE -QUARTER  INCH   CYLINDRICAL   GAGE 
THE  UNITS  ARE  MICRONS 


DEGREES 

CENTI- 
METERS 

FROM 
END 

SET  1                                    SET  II 

A  —  D' 

A 

B 

D  = 

A  +  B 

A* 

W 

D'  =  A' 
+  B' 

-  D 

o 

o-5 

236.9 

197.8 

434-7 

233-5 

201.2 

434-7 

o.o 

I.O 

242.0 

192.6 

434-6 

238.0 

196.7 

434-7 

+   O.I 

i-5 

241.1 

193-5 

434-6 

238.0 

196.7 

434-7 

+    O.I 

2.0 

2344 

199.8 

434-2 

231.0 

2O3.I 

434-1 

—   O.I 

2-5 

226j6 

207.6 

434.2 

233-0 

2  1  1.  2 

434-2 

0.0 

3-° 

235-3 

199.0 

434-3 

231.0 

2O4.2 

434-2 

—    O.I 

45 

°-5 

237.6 

197.0 

434-6 

231.0 

203.6 

434.6 

0.0 

I.O 

233  -o 

191.7 

434-7 

238.0 

196.5 

434-5 

—   O.2 

i-5 

241.0 

193-4 

434-4 

236.5 

197.8 

434.3 

—   O.I 

2.O 

234.0 

20O.2 

434-2 

230.0 

2O4.0 

434-0 

—   0.2 

2-5 

220.0 

208.3 

434-3 

223.0 

211.  2 

434-2 

—   O.I 

3-° 

233-0 

201.3 

434-3 

230.0 

2O4.I 

434-1 

—   0.2 

90 

°-5 

234.0 

200.6 

434-6 

230.0 

204.6 

434-6 

O.O 

I.O 

240.O 

2944 

434-4 

236.0 

I98.5 

434.5 

+    O.I 

i-5 

240.O 

J94-3 

434-3 

237.0 

197.5 

434-5 

+   0.2 

2.0 

233-5 

200.8 

434-3 

230.0 

2O4.2 

434.2 

—   0.1 

2-5 

225.O 

209.1 

434-1 

223.0 

2II.2 

434.2 

+   O.I 

3-o 

233-0 

201.  1 

434-1 

229.0 

205.2 

434-2 

+   O.I 

135 

°-5 

234.0 

200-5 

434-5 

231.0 

203.4 

434-4 

—   O.I 

I.O 

24O.O 

194.6 

434-6 

238.0 

196.5 

434-5 

—   O.I 

i-5 

240.O 

194.3 

434-3 

236.0 

198.3 

434-3 

0.0 

2.0 

233-0 

2OI.O 

434-0 

229.0 

205.2 

434-2 

+   O.I 

2-5 

225.O 

209.2 

434.2 

22I.O 

213.3 

434-3 

+   C.I 

3-° 

234.0 

200.3 

434-3 

229.0 

205.2 

434-2 

—  O.I 

180 

°-5 

235-0 

199.7 

434-7 

225.0 

202.6 

434-6 

—  O.I 

I.O 

237.8 

196.8 

434-6 

238.0 

196.5 

434-5 

—   O.I 

i-5 

239.0 

J95-4 

434-4 

238.0 

196.4 

4344 

0.0 

2.O 

232.0 

202.1 

434.1 

230.0 

2O4.2 

434-2 

-f    O.I 

2-5 

224.O 

201.2 

434.2 

222.O 

2O2.2 

434-2 

0.0 

3-o 

232.0 

202.2 

434-2 

230.0 

204.2 

434-2 

0.0 

GAGES  AND  GAGING   SYSTEMS  71 

MEASURING  CYLINDRICAL  GAGES 

These  are  measured  between  lines  or  edges.  The  screw  ends 
have  cylinders  or  edges  mounted  perpendicular  to  the  screw 
axes.  A  preferable  method  is  to  work  between  the  screw  points, 
and  to  move  the  table  carrying  the  gage  up  and  down  past  the 
screw  points  so  as  to  just  establish  electric  touch  in  passing. 
In  this  way  the  straight  lines  mentioned  above  are  virtual  lines 
due  to  the  passage  of  the  measuring  points  past  the  gage. 

Before  commencing  measurement  the  axis  of  the  gage  is  set 
perpendicular  to  the  screw  axis.  Put  the  gage  on  the  table,  its 
axis  being  horizontal  and  across  the  length  of  the  gage.  Move 
the  gage  by  the  table  till  its  other  end  makes  contact  with  the 
left  screw  end.  If  the  two  contacts  have  identical  micrometer 
readings,  the  gage  is  set. 

The  results  for  a  f-inch  gage  are  shown  in  Table  3. 

Readings  are  made  along  the  gage  at  six  places  from  0.5  to 
3  centimeters  from  one  end.  After  one  set  of  six  readings  the 
gage  is  rotated  on  its  axis  to  position  45  degrees,  90  degrees,  135 
degrees  and  180  degrees  from  the  original  one,  and  for  each  posi- 
tion six  readings  are  taken,  as  before. 

Set  I  takes  about  three  quarters  of  an  hour,  and  is  completed 
before  Set  II  is  commenced;  corresponding  measurements  are  in 
one  line.  In  no  case  do  the  results  of  the  two  sets  differ  by  more 
than  ±  O.2/X. 

The  gage  is  a  very  good  one;  the  differences  in  various  places 
are  not  more  than  o.y/u,  though  there  is  a  distinct  tapering  in 
every  position,  the  handle  end  being  thickest.  There  is  a  slightly 
different  angle  of  taper  in  the  different  positions.  The  180- 
degree  position  results  are  almost  identical  with  those  for 
o-degree  position,  as  they  ought  to  be. 

SENSITIVE  ATTACHMENT  FOR  MEASURING  INSTRUMENTS 

We  have  often  wondered  why  the  system  of  sensitive  measure- 
ment, such  as  is  found  on  a  Bath  indicator,  is  not  more  exten- 
sively used.  No  matter  how  finely  and  accurately  micrometers 
and  verniers  may  be  made,  dependence  must  in  all  cases  be  placed 
on  the  sensitiveness  of  a  man's  hand  to  obtain  the  exact  dimen- 
sions of  the  piece  to  be  measured.  In  order  to  overcome  this 


72  GAGES  AND  GAGING   SYSTEMS 

difficulty  and  eliminate  the  personal  equation  in  the  manufacture 
of  duplicate  and  interchangeable  parts,  we  have  tried  the  sensi- 
tive attachment  to  the  micrometer  shown  in  Fig.  67,  and  found  it 
of  much  value. 

The  auxiliary  barrel  A  is  held  to  the  anvil  of  the  micrometer 
by  means  of  a  thumb-screw  B.  In  the  inside  end  of  the  barrel 
is  a  secondary  anvil  C,  the  base  of  which  bears  against  the  short 
arm  of  the  indicating  lever  D.  The  action  will  clearly  be  seen 
by  reference  to  the  cut.  The  micrometer  is  so  set  that  when  a 
g-age,  G,  of  exact  size  is  placed  between  the  measuring  points, 
the  long  arm  of  the  indicator  stands  at  the  o  mark.  If  the  pieces 
being  calipered  vary  in  the  least  from  the  standard  size,  it  will 
be  readily  noted  by  the  movement  of  the  pointer.  Hard  rubber 
spheres  turned  from  rough  were  found  to  vary  from  3  to  5  thou- 
sandths after  having  passed  the  inspector's  test  with  an  ordinary 


FIG.  67.  —  Special  Micrometer. 

micrometer.  With  this  attachment  the  inspector's  helper  could 
detect  very  minute  variations  from  the  limit  size.  The  same 
device  was  used  to  gage  the  size  of  all  brass  disks  about  half  the 
diameter  of  the  rubber  spheres,  and  in  fact  anything  within  the 
limit  of  the  micrometer  can  be  made  to  show  to  the  naked  eye 
variations  as  small  as  a  ten  thousandth.  Considerable  trouble 
was  experienced  with  a  pair  of  small  brass  miter  gears,  because 
of  the  difficulty  of  getting  the  outside  diameter  just  right. 
Inasmuch  as  they  were  finished  on  a  screw  machine,  some  of  the 
holes  were  not  concentric  with  the  face,  causing  the  gears  to  bind. 
Fig.  68  shows  a  gage  which  was  quite  inexpensive  and  at  the  same 
time  showed  up  the  slightest  inaccuracy. 

A  DEVICE  FOR  TESTING  GAGES 

In  some  shops  certain  thin  bow-back  gages  are  used,  which 
will  get  out  of  true  if  accidentally  dropped,  or  if  a  light  rap  is 


GAGES  AND  GAGING   SYSTEMS 


73 


given  to  the  machine.  When  it  happens  the  inspector  will  take 
a  two-foot  rule,  try  the  gage,  and  finally  send  it  to  the  tool-room 
for  repair.  Here  the  tool-man  tries  it  on  a  steel  rule,  gets  the 
mate  to  it,  and  adjusts  them  by  peening.  We  have  here  in 
Figs.  69  and  70  a  micrometer  caliper  which  was  designed  several 
years  ago  for  the  purpose  of  testing  gages  such  as  these. 

The  caliper  will  test  both  inside  and  outside  gages.  Piece  A, 
Fig.  70,  can  be  adjusted  to  any  inch  on  the  bar  by  loosening  thumb- 
nut  B,  and  the  desired  inch  can  be  located  through  the  opening 
C.  The  adjustments  for  thousandths  can  be  taken  from  the 
micrometer  adjustment  at  the  other  end.  D,  Fig.  69,  is  a  support 
for  the  bar  and  can  be  removed  along  the  bar  when  necessary. 
This  caliper  can  be  used  to  set  inside  and  outside  calipers. 


FIG.  68. —  Bevel  Gear  Gage. 

A  TESTING  TOOL  FOR  FINE  WORK 

The  sketch  Fig.  71  shows  a  very  fine  tool  for  testing  work 
to  .0001  inch  and  less;  you  can  measure  much  closer  with  this 
than  with  micrometers.  The  jaws  are  i  inch  long,  are  .001  inch 
farther  apart  at  the  point  than  at  the  back,  and  the  fixed  jaw  is 
graduated  in  tenths  on  one  side;  thus  variations  of  .001  inch  or 
less  may  be  detected  in  work  placed  between  the  jaws.  Say  we 
have  a  piece  to  test,  like  the  one  shown  in  the  sketch,  to  see  if 
its  faces  are  perfectly  parallel;  move  the  jaws  down  on  the  work, 
say,  4,  5  or  6,  and  try  all  four  corners  and  see  if  they  come  to  the 
same  point.  If  they  do,  the  piece  is  exact.  If  not,  whatever  is 
out  is  plainly  shown  by  the  graduations.  Any  one  with  fine 
work  to  do  will  appreciate  this  tool.  We  thought  we  could  grind 
them  close  enough  with  our  micrometers,  but  we  could  not,  so 
we  made  one  of  these  tools  and  it  worked  admirably.  You  will 
be  surprised  to  see  how  closely  you  can  measure  with  it.  This 
tool  must  be  hardened  and  ground  all  over. 


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GAGES   AND   GAGING   SYSTEMS 


75 


A  ROLL  GAGE 

The  engraving,  Fig.  72,  shows  a  gaging  implement  which  has 
been  devised  especially  for  gaging  rolls,  such  as  are  used  in  the 
cold  rolling  of  sheet  metal,  where,  as  our  readers  know,  very 
great  accuracy  is  often  required.  The  gage  consists  essentially 
of  a  curved  plate,  which  rests  on  top  of  the  roll  to  be  gaged. 
Rising  from  the  center  of  this  plate  is  a  cylindrical  standard 
having  graduations  upon  it,  and  attached  to  a  piece  sliding  upon 
this  standard  there  is  a  swinging  bar  which  is  graduated  and 
carries  two  measuring  jaws.  The  one  at  the  left  is  plain  and 
solid,  while  the  one  at  the  right  is  made  of  an  open  framework, 
and  with  a  contact  piece  attached  to  the  short  arm  of  a  multi- 
plying lever  which  is  connected  to  the  shorter  arm  of  a  second 


FIG.  71.  —  Tool  for  Accurate  Testing. 

multiplying  lever,  which  indicates  variations  of  diameter  on  the 
curved  scale  shown  above,  the  graduations  of  this  scale  being  to 
half-thousandths.  In  using  the  gage  the  horizontal  beam  is  set 
on  the  standard  to  the  nominal  diameter  of  the  roll,  as  indicated 
by  the  graduations  on  the  standard.  The  left-hand  jaw  is  set 
also  to  the  graduation  corresponding  to  the  nominal  diameter 
of  the  roll  and  the  right-hand  jaw,  so  that  at  the  beginning  of 
measurement  the  point  will  indicate  zero.  Then  when  the  gage 
is  moved  endwise  upon  the  roll,  any  variation  of  diameter  is  shown 
upon  the  graduated  scale.  The  horizontal  arm  is  free  to  swing 
in  a  vertical  plane  during  this  process.  Usually  the  lower  roll 
is  not  truly  cylindrical,  but  is  largest  in  the  middle,  there  being 
a  straight  or  cylindrical  section  in  the  middle  with  slightly  taper- 
ing sections  at  each  end,  the  result  being  that  when  pressure  is 
put  on  the  rolls,  the  upper  line  of  the  lower  roll  is  practically 


76 


GAGES   AND   GAGING   SYSTEMS 


straight  and  the  metal  is  rolled  to  practically  uniform  thickness. 
This  gage  is  especially  adapted  for  indicating  when  the  designed 
taper  has  been  secured;  the  grinder's  experience  telling  him  what 
the  proper  taper  is.  The  object  of  making  the  flat-hand  jaw 
solid  is  that  it  may  be  the  heavier,  so  that  placing  the  finger 


FIG.  72.  —  Instrument  for  Gaging  Rolls. 

upon  the  horizontal  bar  at  the  right  and  swinging  this  bar  slightly, 
the  contact  points  are  made  to  pass  over  the  largest  diameter 
of  the  roll.  All  the  contact  pieces  are  made  cylindrical,  but  do 
not  turn  freely.  They  can,  however,  be  turned  by  loosening  the 
screws  so  as  to  bring  fresh  contact  surfaces  in  use  when  the 
instrument  has  become  worn. 


GAGES  AND  GAGING   SYSTEMS  77 

A  NEW  ENGLISH  TYPE  OF  UNIVERSAL  LIMIT  GAGE 

Fig.  73  shows  the  Newall  working  gage  with  its  adjusting  dial 
and  zero  in  position.  The  pair  of  contact  points  at  the  left  is 
fixed  in  position,  but  the  pair  at  the  right  is  adjustable  by  a  screw- 
driver. One  of  the  opposing  pairs  of  points  is  intended  for  the 


FIG.  73.  —  English  Universal  Limit  Gage. 

lower  and  the  other  for  the  upper  limit  of  the  piece  for  which 
the  gage  is  to  be  adjusted.  When  adjusting  the  gage  both  pairs 
of  points,  with  dial  and  zero  removed,  are  first  adjusted  to  true 
size  by  a  standard  plug  gage  —  a  set  of  such  plugs  being  all  that 
is  required  in  the  way  of  fixed  gages.  The  setting  dial  and  zero 
-shown  to  larger  scale  in  Fig.  74  —  are  then  slipped  over  the 
contact  points  as  shown  in  Fig.  73,  and  by  a  screw-driver  the 
point  which  carries  the  dial  is  adjusted  the  required  amount  above 


78  GAGES  AND   GAGING   SYSTEMS 

or  below  the  standard  to  give  the  lower  limit  of  size,  and  is  then 
locked.  The  dial  and  zero  are  then  reversed  and  the  outer  point 
is  adjusted  to  the  upper  limit  of  size.  The  fit  of  dial  and  zero 
on  the  screw  points  is  by  a  taper,  such  that  pressure  with  the 
thumb  will  fasten  them  in  position  securely  enough  for  the  purpose. 
The  dial  reads  both  ways  from  zero,  in  order  to  provide  for  set- 
ting the  gage  above  the  plug  size  for  a  forced  fit,  or  below  it  for 
a  running  fit. 


FIG.  74.  —  Dial  of  Limit  Gage. 

GAGE  FOR  MEASURING  HAIR  LINES  ON  TYPE  FACES 

The  drawing,  Fig.  75,  shows  a  device  for  measuring  hair  lines 
on  the  faces  of  type,  which  we  made  a  few  months  ago  for  a  type- 
making  firm.  We  take  it  for  granted  that  it  is  all  right  and  fills 
the  bill,  as  we  have  never  heard  from  it  since  it  was  finished. 
The  sketch  is  drawn  from  memory,  and  is  only  intended  to  show 
the  principle  of  it. 

A  is  a  block  of  tool  steel  made  in  the  shape  shown  and  worked 
up  true  with  the  hole,  which  receives  the  adjusting  screw  E  and 
micrometer  screw  G,  also  the  rod  F.  The  block  B  is  then  made 
and  ground  true  with  the  hole,  which  is  tapped  any  fine  pitch, 
from  24  to  40,  as  it  is  only  for  adjusting.  The  block  has  about 
J  inch  of  thread  for  the  screw,  while  the  remainder  is  bored  out 
to  receive  the  spring  H.  The  bottom  of  the  block  must  have  a 
nice  even  bearing  where  it  is  in  contact  with  the  main  block,  also 
in  the  holes,  and  must  work  very  nicely  and  without  the  least 


GAGES  AND  GAGING  SYSTEMS 


79 


shake.  The  plate  /  is  a  piece  of  tool  steel,  hardened  and  ground, 
and  lapped  to  a  nice  straight  edge  on  line  /.  The  corresponding 
line  or  face  against  which  the  type  rests  is  also  lapped.  The  plate 
/  is  beveled  off  to  a  knife-edge  and  must  fit  nicely  along  the  main 
block,  the  type  when  in  place  just  high  enough  to  allow  it  to 
pass  over.  The  block  D  is  fitted  and  pinned  to  the  rod  F,  which 
is  also  a  nice  fit  in  the  holes,  and  on  the  bearing  face  represented 
by  line  K,  and  is  pushed  forward  by  spring  L  against  the  type  to 
hold  it  in  place  while  the  measures  are  being  taken.  The  mi- 
crometer barrel  was  sawed  from  a  half-inch  micrometer,  turned 


FIG.  75.  —  Gage  for  Type  Faces. 

to  fit  the  block  and  pinned  with  a  small  taper  pin.  The  screw  E 
should  be  a  tight  fit  in  the  block  B,  so  that  when  it  is  once  set 
there  will  be  no  liability  of  its  turning.  The  screw  should  be 
threaded  about  f  inch  to  allow  for  adjusting  the  block  B,  which, 
when  the  micrometer  screw  is  at  o  or  zero,  is  brought  so  that  it 
is  exactly  on  the  line  /,  and  should  not  be  moved  unless  in  case 
of  wear  on  the  ends  of  the  screws,  as  they  are  always  in  contact. 
Now  let  W  represent  a  type  in  place  ready  to  be  measured.  The 
micrometer  screw  is  turned  to  the  right^followed  by  the  block  B, 
until  the  knife-edge  on  /  is  at  a  point  where  the  operator  wishes 
to  take  his  reading,  which  is  done  with  the  aid  of  a  very  strong 
glass. 


8o 


GAGES  AND  GAGING   SYSTEMS 


A  DEVICE  FOR  TESTING  SQUARES 

Another  testing  device  which  we  noticed  in  a  machine  shop 
attracted  our  attention,  and  this  is  shown  at  Figs.  76  and  77. 


FIG.  76.  —  Square  Testing  Device. 

The  system  of  inspection  in  these  shops  is  very  rigid.  Every 
piece  is  inspected  as  the  different  operations  on  it  are  completed 
upon  it,  and,  of  course,  in  doing  this  squares  are  used  where 
necessary.  There  were  constant  complaints  of  the  work  not 


GAGES  AND  GAGING  SYSTEMS 


81 


coming  square  from  the  milling  machines  and  the  planers,  and  in 
very  many  cases  where  the  inspectors  declared  a  piece  to  be  "out 
of  square,"  and  it  was  returned  to  the  workman,  he  was  able  to 
show  that  by  the  square  he  had  used  —  and  which  had  been 
supplied  to  him  from  the  tool-room  —  the  piece  was  square. 
An  investigation  disclosed  the  fact  that  a  piece  might  really 
be  right  by  one  square  and  a  little  off  by  another,  and  the  trouble 
was  thus  traced  to  the  squares  themselves,  although  these  had 
come  from  the  same  establishment  and  were  believed,  and  for 
the  same  matter  are  still  believed,  to  be  the  best  and  most 
accurate  squares  that  are  to  be  purchased  anywhere.  So  the 
device  Figs.  76  and  77  was  made  to  test  squares  and  to  enable 


po- 


FIG.  77.  —  Square  Testing  Device. 

them  to  be  corrected  when  found  slightly  out.  The  surface 
plate  which  forms  the  plate  of  the  device  was  carefully  fitted  by 
scraping  to  an  original  plate,  and  at  the  back  of  this  it  attached 
a  standard  which  supports  a  straight-edge  that  has  its  sides  as 
nearly  straight  and  parallel  with  each  other  as  it  was  possible  to 
make  them.  This  is  adjustable  vertically  through  a  small  dis- 
tance, so  that  the  lower  end  of  it  can  be  brought  close  to  the 
stock  of  a  square  placed  upon  the  surface  plate  when  testing  the 
inside  edge,  or  close  to  the  surface  plate  when  testing  the  outside 
side  of  a  square  blade.  At  each  edge  of  the  straight-edge,  but 
just  back  of  it,  a  long  narrow  mirror  is  placed.  These  mirrors 
swivel  on  pivots  at  top  and  bottom,  so  that  the  light  which  strikes 
them  can  be  reflected  to  pass  through  the  opening  between  a 


82  GAGES  AND  GAGING   SYSTEMS 

square  blade  and  the  edge  of  the  straight-edge,  if  there  is  any 
such  opening;  and  when  the  straight-edge  has  been  adjusted  by 
means  of  knurled  head  screws,  provided  for  that  purpose,  so 
that  one  edge  of  it  exactly  shuts  out  the  light  between  itself  and 
the  square  blade,  the  square  is  swung  around  to  bring  the  same 
edge  of  the  blade  against  the  opposite  edge  of  the  straight-edge. 
This  of  course  shows  double  the  error  that  actually  exists,  and 
the  square  is  then  lapped  until  it  will  stand  this  test.  It  is  now 
found  that  when  an  inspector  declares  a  piece  to  be  out  of  square, 
it  will  be  found  to  be  out  also  by  the  square  the  workmen  used; 
in  other  words,  the  squares  now  agree  with  each  other.  It  is, 
of  course,  a  very  refined  test,  and  the  device  is  beautifully  made 
and  finished.  A  drawing  of  the  device  is  shown  at  Fig.  77,  which, 
however,  does  not  show  the  mirrors,  one  of  which  is  seen  in  the 
engraving,  Fig.  76.  Perhaps  they  were  added  to  strengthen 
the  light  after  the  device  was  made.  In  adjusting  the  straight- 
edge to  agree  with  a  square  being  tested,  it  swivels  upon  the 
pivot  seen  near  the  top  of  the  standard  in  the  drawing,  and  the 
adjusting  screws  are  graduated  to  read  to  .001  millimeter  per 
foot  of  length,  and  this,  of  course,  enables  errors  to  be  known  in 
definite  terms  of  magnitude. 

MICROMETER  HEADS  FOR  SPECIAL  GAGES 

Considerable  use  is  now  being  made  of  micrometer  heads  on 
special  gages  of  various  kinds,  and  as  the  advantages  of  these 
applications  become  more  widely  known,  the  use  of  these  heads 
will  undoubtedly  increase.  Their  convenience  of  application  to 
gages  of  various  sorts,  and  the  fact  that  they  enable  the  varia- 
tion from  the  exact  size  to  be  read  in  thousandths,  render  them 
superior  in  many  cases  to  limit  gages  of  the  usual  kind,  and  they 
are  moreover  applicable  to  a  great  variety  of  uses  to  which  the 
usual  fixed  type  gages  would  hardly  be  applied  at  all.  Such 
gages  are  comparatively  cheap,  as  the  heads  supply  much  of  the 
really  accurate  work  ready  made,  and  they  cost  but  little. 

At  the  beginning,  and  in  many  cases  still,  these  heads  were 
obtained  by  cutting  off  the  yoke  of  a  complete  micrometer  caliper, 
but  they  are  now  being  supplied  by  various  makers  without  the 
yoke.  Fig.  78  shows  one  of  these  heads  as  made  by  J.  T.  Slo- 
comb  &  Co.,  of  Providence,  R.  I.,  which  does  not  differ  from 


GAGES  AND  GAGING   SYSTEMS  83 

the  head  of  a  complete  caliper,  except  that  it  has  turned  and 
flanged  seat  for  insertion  in  an  eye  of  the  special  gage  to  which 
it  is  to  be  applied  —  the  attachment  of  the  head  to  the  body  of 
the  gage  being  by  soft  solder. 

Fig.  79  shows  a  cross-section  of  the  head  and  illustrates  a 
feature  of  the  Slocomb  head  which  renders  it  especially  applicable 
to  this  use,  namely,  the  provision  for  adjusting  for  wear  in  order 
to  preserve  the  zero,  which,  it  will  be  seen,  is  in  the  head  itself. 


FIG.  78.  —  Micrometer  Head. 

The  main  nut  a  is  threaded  into  the-  barrel  by  a  screw  having 
thirty-two  threads  per  inch,  and  as  the  measuring  screw  has 
forty. threads  per  inch  it  will  be  seen  that  by  turning  the  nut  in 
the  barrel  the  screw  is  adjusted  along  the  barrel  by  the  differen- 
tial action  of  the  two  threads  —  this  action  being  such  as  to  give 
a  movement  of  .0062  per  revolution.  Another  feature  of  this 
head  is  the  supplementary  nut  b,  which  is  fitted  with  a  row  of 
V-shaped  teeth  on  the  end  which  faces  the  main  nut  a,  these 
teeth  engaging  corresponding  teeth  in  the  main  nut.  By  first 


FIG.  79.  —  Micrometer  Head. 

withdrawing  the  screw  and  then  turning  nut  b  one  or  more  teeth, 
any  looseness  imthe  threads  due  to  wear  may  be  taken  up.  Still 
another  feature  is  the  insertion  of  a  light  spring  between  nuts  a 
and  b,  the  object  of  which  is  to  put  a  slight  friction  on  the  screw 
and  thus  prevent  its  accidental  displacement. 

Fig.  80  shows  an  instrument  which  is  used  in  rebabbitting  or 
otherwise  re-establishing  the  journals  of  a  lathe  headstock. 
The  micrometer  head  is  carried  by  a  ring  which  is  so  jointed  to 
the  stock  of  the  tool  as  to  turn  upon  it,  and  thus  permit  readings 
to  be  taken  vertically  or  horizontally.  One  end  of  the  babbitting 


GAGES  AND  GAGING   SYSTEMS 


or  testing  mandrel  is  shown  in  position,  the  live  spindle  of  the 
lathe  being  supposed  to  be  removed.     It  is  obvious  that  with  a 


FIG.  80.  —  Testing  Parallelism  of  Lathe  Centers. 

suitable  support  at  the  headstock  end  of  the  mandrel,  it  may 
by  these  means  be  adjusted  to  exact  parallelism  with  the  V's  of 
the  lathe. 


FIG.  81.  —  Gaging  Bevel  Gear  Faces. 

Fig.  8 1  shows  a  gage  for  determining  the  proper  location  of 
the  bevel  faces  of  bevel  gears  in  relation  to  the  hub  face.  This 
test  is  in  reality  applied  to  the  blanks  before  the  teeth  are  cut, 


GAGES   AND   GAGING   SYSTEMS  85 

but  by  an  oversight  the  photograph  was  taken  with  a  completed 
gear  in  the  gage. 

Fig.  82  shows  a  tool  of  obvious  utility  in  determining  the 
degree  of  truth  in  a  planer  table.  Other  obvious  uses  for  it  are 
in  boring  mill  and  drill  press  tables  and  to  lathe  face-plates. 

Fig.  83  shows  a  fixture  for  determining  the  correct  diameter 
of  the  ball  race  in  the  crank  shaft  gear,  back  of  the  teeth,  and 
under-cut  so  that  the  direct  application  of  fixed  gages  is  im- 
possible. The  gear  is  mounted  on  the  spindle  carried  in  the 


FIG.  82.  — Testing  Truth  of  Planer  Table. 

left-hand  head  of  the  fixture,  and  is  carried  longitudinally  in  the 
spindle  bearing  against  an  adjustable  stop,  which  when  once 
established  is  permanent.  The  abutment  gage  for  the  ball  race 
is  in  front  of  the  gear,  and  the  spindle  bearing  has  a  transverse 
sliding  movement,  permitting  the  ball  race  to  be  brought  into 
contact  with  the  stop  gage,  when  the  micrometer  may  be  read 
-the  adjustment  being  preferably  such  that  the  reading  when 
the  work  is  exactly  right  is  zero.  It  will  be  noticed  that  in  this 
case,  as  in  the  others,  the  micrometer  not  only  tells  if  the  work 
is  right,  but  if  wrong  it  tells  by  how  much,  and  furthermore,  the 
limits  between  which  the  work  is  done  may  be  determined  after 


GAGES  AND  GAGING    SYSTEMS  87 

the  gage  is  made  and  increased  or  diminished,  if  found  advisable, 
instead  of  being  —  as  with  fixed  gages  —  determined,  and  per- 
haps unwisely,  before  the  gage  is  made. 

Fig.  84  shows  a  gage  for  measuring  the  taper  seats  of  a  crank 
bracket  in  which  the  taper  ends  of  the  frame  tubes  are  inserted. 
Certain  diameters  of  these  seats  are  required  to  be  at  proper 
distances  from  the  axis  of  the  bracket,  and  the  accuracy  of  this 
is  determined  by  the  insertion  of  a  taper  plug  —  seen  separate 
at  the  left  —  and  then  taking  a  reading  with  the  micrometer. 


SECTION   III 

LATHE,   PLANER,   SURFACE,   AND   UNIVERSAL  GAGES 
AND  INDICATORS;  THEIR  CONSTRUCTION  AND  USE. 

SIMPLE  AND  INEXPENSIVE  LATHE  INDICATORS 

AFTER  being  neglected  for  a  number  of  years,  it  is  well  that 
at  last  the  value  and  economy  in  the  use  of  indicators  in  the  tool, 
jobbing  and  manufacturing  shops  are  becoming  recognized  and 
appreciated.  A  knowledge  on  the  part  of  the  mechanic  of  the 
uses  and  adaptability  of  the  various  designs  of  these  handy  and 
accurate  tools  will  enable  him  to  turn  out  more  and  better  work 
with  less  effort  and  worry  on  his  part  than  he  possibly  imagines. 
Their  use  guarantees  the  accurate  location  and  running  of  the 
work  in  hand,  and  insures  against  error  through  neglect  in  having 
the  fundamental  placing  correct.  There  is  no  guesswork  where 
indicators  are  used. 

A  very  simple  and  comparatively  inexpensive  lathe  indicator 
can  be  constructed  on  lines  similar  to  the  one  shown  in  Fig.  85. 
It  is  simply  a  rod  centered  to  fit  the  lathe  centers,  or  one  lathe 
center  and  the  work,  as  the  case  may  be,  and  a  needle  or  a  surface 
gage.  It  can  be  used  in  a  variety  of  ways.  For  instance,  to 
chuck  a  piece  of  work  to  be  bored  on  the  carriage  place  one  end 
against  the  center  punch  mark  which  locates  the  hole,  and  the 
other  on  the  live  centers;  if  the  needle  does  not  travel  parallel  to 
the  face-plate  the  work  is  not  chucked  true.  It  may  be  necessary 
to  turn  the  face-plate  and  needle  together  if  the  face-plate  is  not 
true.  Of  course  this  will  locate  only  one  point  of  the  work,  and 
care  must  be  taken  to  chuck  the  piece  so  that  the  other  end  of 
the  hole  will  come  where  it  is  wanted. 

By  having  suitable  centers  in  the  ends  of  the  rod,  it  can  be 
used  to  set  the  tailstock  center  in  line.  The  method  is  the  same. 
Sometimes  it  can  also  be  used  to  advantage  in  chucking  work 
on  the  face-plate,  as  it  is  easier  to  rotate  the  light  indicator  than 


GAGES  AND  GAGING  SYSTEMS 


89 


to  pull  a  heavy  face-plate  round.  This  is  especially  true  when 
the  work  is  liable  to  upset  your  calculations  by  sliding  off  on  the 
ways.  For  everything  except  the  last  case  the  rod  should  be 
short  in  order  to  magnify  the  error  as  much  as  possible.  The 
live  center  should  also  be  true. 


FIG.  85.  —  Simple  Lathe  Indicator. 

A  UNIVERSAL  LATHE  INDICATOR 

Figs.  86  and  87  illustrate  a  universal  indicator  of  novel  and 
ingenious  construction.  It  consists  of  a  machine  steel  holder  A, 
\  x  i  inch,  carrying  on  its  head  a  graduated  arc  B  and  pointer  C, 
both  held  in  position  by  a  knurled  thumb-screw  (not  shown), 


DH.12J 


FIG.  86.  —  Universal  Indicator. 

which  binds  the  arc  to  the  holder,  but  allows  the  pointer  to  play 
over  the  face  of  the  arc. 

To  the  side  of  A  is  firmly  bound  a  stiff  spring  D,  which  in 
turn  carries  near  its  upper  edge  a  boss  or  hollow  sleeve  E,  holding 
a  sliding  pin,  which  works  against  the  short  arm  of  the  pointer 
at  a.  This  is  for  testing  the  face  of  the  work  held  in  the  chuck 
or  on  a  mandrel,  or  to  find  whether  a  piece  on  the  center  is  out  of 
round. 


90  GAGES  AND  GAGING   SYSTEMS 

To  the  outer  end  of  D  is  secured,  by  means  of  a  knurled  thumb- 
screw, the  slotted  pin  F,  carrying  the  yoke  G,  both  together 
making  a  universal  joint  which  carries  the  long,  light  pointer  or 
needle  for  testing  by  center  punch  mark  in  the  usual  way. 

By  binding  the  needle  in  the  yoke  through  means  of  the 
thumb-screws  to  prevent  side  motion,  and  adjusting  the  spring 
and  joint  by  means  of  thumb-screws  b  and  c,  the  needle  is  brought 
into  position  to  test  the  truth  of  the  hole. 

All  parts  are  detachable  when  not  needed  by  simply  removing 
their  respective  thumb-screws. 


FIG.  87.  —  Universal  Indicator. 

A  DECIMALLY  GRADUATED  UNIVERSAL  INDICATOR 

Figs.  88,  89  and  90  show  a  front  elevation  and  a  vertical 
transverse  section  of  an  extremely  complete  and  accurate  universal 
indicator  as  attached  to  an  angular  steel  base,  and  in  use  as  a 
depth  gage.  The  construction  is  as  follows:  A  tubular  body  or 
shell  a,  through  the  center  of  which  a  rod  b  passes  and  is  held  in 
any  desired  position  by  the  friction  collar  c,  which  is  slotted  at  d. 
The  friction  collar  c  is  fitted  free  in  the  enlarged  bore  of  a  with  a 


GAGES  AND  GAGING   SYSTEMS 


91 


limited  amount  of  longitudinal  movement,  and  is  held  in  the 
shell  by  the  plug  e,  which  is  fitted  tight.  The  shell  is  cut  away 
to  give  a  flat  surface  on  one  side  for  the  placing  of  the  indicator 
needle  and  spring.  Indicator  needle  /  is  pivoted  to  the  shell  by 
a  small  screw  at  g,  the  heel  of  the  needle  bearing  on  the  friction 
collar  c  by  the  pressure  of  the  feather  spring  h.  The  spring  is 
"sweat"  into  a  small  slot  in  the  needle,  and  rests  against  the 
pin  /.  The  needle  point  is  shown  about  in  its  normal  position, 


FIGS.  88  and  89.  —  Decimally  Graduated  Indicator. 

with  the  friction  collar  resting  on  the  plug  e.  An  upward  move- 
ment of  the  rod  b  and  friction  collar  c  would  move  the  needle 
point  to  the  right.  Scale  ;  is  graduated  to  read  approximately 
to  thousandths  of  an  inch,  within  a  range  of  twenty-five  thou- 
sandths. 

The  tools  are  applied  to  the  ordinary  surface  gage  as  illustrated 
in  Fig.  90.  A  taper  hole  in  the  body  or  shell  at  k  provides  means 
of  attaching  it  to  the  wire  rod  of  the  surface  gage.  The  engrav- 
ings show  the  operation  of  taking  the  deflections  from  end  to 
end  of  the  cross  rail  of  a  planer  from  the  platen. 


92  GAGES  AND  GAGING   SYSTEMS 

The  slot  at  w,  Fig.  89,  may  be  used  in  connection  with  a  steel 
rule  or  the  blade  of  a  square.  The  tool-maker  will  find  many 
other  uses  for  the  instrument  than  those  herein  shown,  such  as 
testing  a  lathe  center,  showing  the  amount  of  wear  of  tool  slides, 
leveling  work  in  the  milling  machine  or  planer,  inspection  of 
finished  work,  etc.  The  indicator  may  be  carried  in  the  vest 


FIG.  90.  —  Decimally  Graduated  Indicator. 

pocket,  its  weight,  without  the  rod,  being  three  quarters  of  an 
ounce.  The  inventor  of  this  handy  tool  is  Charles  E.  Hauer,  a 
tool-maker,  and  foreman  in  the  factory  of  the  Westinghouse 
Electric  &  Manufacturing  Company. 


A  LATHE  AND  PLANER  INDICATOR 

The   following  description   of  a   lathe   and   planer  indicator 
refers  to  the  one  illustrated  in  Figs.  91  and  92.     It  is  unexcelled 


GAGES  AND  GAGING   SYSTEMS 


93 


u 


o 


94 


GAGES  AND  GAGING   SYSTEMS 


for  the  work  for  which  it  was  designed.  It  is  graduated  to  in- 
dicate thousandths,  and  by  multiplication  of  the  needle  move- 
ment by  compound  levers,  the  slightest  error  is  easily  detected. 
The  projecting  barrel  A  allows  the  feeler  B  to  be  used  in  a  very 
contracted  space  and  in  deep  holes.  The  end  of  the  barrel  is 
tapered  and  the  holder  for  the  feeler  B  fits  over  it.  The  position 
of  the  feeler  relative  to  the  barrel  may  be  changed  by  simply 
twisting  it  round.  The  movement  of  the  feeler  is  transmitted 
through  F  to  the  lever  D,  which  is  restrained  by  the  spring  G, 


FIG.  93.  —  Adjusting  Surface  Gage. 

and  which  engages  the  pointer  C.  The  body  of  the  holder  fits 
in  an  ordinary  tool-post.  The  cut  is  nearly  a  full  size  reproduc- 
tion of  the  indicator. 

To  ADJUST  THE  NEEDLE  OF  A  SURFACE  GAGE 

To  set  the  gage,  Fig.  93,  from  the  table,  get  somewhere  within 
one  quarter  inch  of  the  mark  on  the  square.  With  the  thumb 
and  forefinger  on  the  crook  A,  turn  the  needle  until  it  reaches  the 
point  desired.  By  turning  the  needle  it  will  travel  in  the  path 
indicated  by  the  dotted  lines  shown,  on  account  of  the  bend 
near  the  point. 


GAGES  AND  GAGING  SYSTEMS 


A  TOOL-MAKER'S  SCRATCH  BLOCK 


95 


A,  Fig.  94,  is  the  body  or  block  which  is  bored  to  receive  the 
shaft  B,  to  which  is  keyed  the  worm  gear  C,  this  being  held  against 
the  shoulder  by  the  sleeve  J,  which  screws  in  to  the  block  far 
enough  to  make  a  bearing  on  the  outer  shoulder  and  still  let  the 
worm  gear  and  shaft  work  easily  without  end  thrust.  The  shaft 
B  also  shoulders  in  the  block  at  M,  and  when  the  nut  /  is  tight- 
ened on  the  sleeve  J,  the  gear  and  shaft  must  be  free  to  turn  with- 


JIG.  94.  —  Tool-Maker's  Scratch  Block. 


out  end  play.  H  is  a  washer,  or  rather  two  half  washers,  drilled 
when  together  to  receive  the  pointer  K,  the  thumb-nut  G  binding 
the  pointer,  at  the  same  time  bringing  the  back  of  the  washer 
against  the  shoulder  on  B,  which  is  just  flush  with  the  face  of  the 
block,  but  not  allowing  the  washer  to  bind  on  the  block. 

The  shaft,  gear,  washer,  pointer,  and  all  now  being  free  to 
turn,  after  being  set  very  near  and  before  the  pointer  is  tightened, 
may  be  worked  as  desired  by  the  worm  D,  the  end  of  which  fits 
into  the  conical  bearing  O,  and  is  held  in  position  by  the  sleeve  E 
which  screws  into  the  block  and  against  the  shoulder  on  D,  so 
that  it  will  turn  easily  without  any  end  play.  The  knurled  head 


96  GAGES  AND   GAGING   SYSTEMS 

F  is  pinned  by  the  taper  cross-pin  L  to  the  worm.  The  worm 
wheel  was  made  with  a  £-inch  24-thread  master  tap  in  the  lathe. 
Any  one  wishing  to  make  a  scratch  block  will  find  this  to  be  a 
very  good  one. 

A  CHEAP  SURFACE  GAGE 

The  principal  part  of  the  gage  Fig.  95  is  made  from  an  old 
pair  of  calipers.  A  is  a  small  base,  with  a  slot  milled  down  the 
center  for  one  leg  of  the  caliper,  which  is  then  held  in  by  pins. 
B  is  a  reinforcement  on  the  other  leg  so  as  to  make  it  strong  enough 
to  hold  the  scriber  C.  The  base  is  cut  away  at  D  to  admit  the 
stud  on  the  caliper.  With  the  split  nut  a  fine  adjustment  is 
obtained  as  well  as  a  quick  one. 


FIG.  95.  —  Cheap  Surface  Gage. 

A  SURFACE  GAGE  AND  INDICATOR 

Fig.  96  show  a  surface  gage  and  indicator  with  a  number  of 
features  not  usually  found  and  embodied  in  such  instruments. 
It  will  be  noticed  in  the  first  place  that  the  post  or  spindle  has  a 
taper  fit  in  the  base,  the  latter  therefore  being  removable,  and 
as  there  is  a  good  center  in  each  end  of  the  spindle,  the  instrument 
may  be  used  upon  the  lathe  centers,  as  well  as  upon  planers, 
shapers,  milling  machines  and  elsewhere.  The  scriber  used,  it 
will  be  noticed,  is  shown  in  the  sketch  with  a  minute  prick  punch 
in  the  lower  end  of  it.  This  punch  is  normally  held  up  against 
a  shoulder  by  a  little  helical  spring,  a  tap  with  a  light  hammer 
bringing  it  down  to  make  its  mark  when  required.  The  scriber 


FIG.  96.  —  Surface  Gage  and  Indicator. 


98  GAGES   AND  GAGING   SYSTEMS 

may  be  usually  set  in  such  a  direction  as  to  bring  the  prick  punch 
perpendicular  to  the  surface  with  which  it  is  at  the  time  con- 
cerned. The  scriber  is  of  course  reversed  end  for  end  when  lining 
is  to  be  done. 

Upon  the  spindle  are  fitted  the  two  split  sleeves  which  may 
be  clamped  at  any  point  by  their  respective  screws.  The  upper 
of  these  may  be  called  the  fixed  sleeve,  and  the  lower  the  adjustable 
sleeve.  The  sleeves  are  normally  held  apart  by  the  compression 
spring  and  drawn  toward  each  other  in  opposition  to  the  spring 
by  a  long  stud  so  fixed,  screw  attached  to  the  lower  sleeve  and  a 
milled-head  nut  fitted  to  it,  which  bears  upon  a  shoulder  on  the 
upper  side  of  the  upper  sleeve.  The  thread  of  the  screw  is  40  to 
the  inch,  and  the  periphery  of  the  nut  having  25  divisions,  the 
reading  is  in  thousandths  of  an  inch.  The  nut  is  extended  up- 
ward into  a  closed  thimble  which  entirely  covers  the  end  of  the 
screw.  The  upper  sleeve  being  clamped  securely,  the  screw  of 
the  lower  sleeve  may  be  loosened  just  enough  to  permit  the  lower 
sleeve  and  its  appurtenances  to  be  moved,  and  the  movement  is 
indicated  by  the  reading  of  the  nut.  The  adjustable  sleeve 
carries  the  scriber  in  front,  which  may  be  clamped  in  any  position, 
as  shown.  At  the  back  it  carries  a  mounting  for  the  surface 
indicator,  which  is  used  for  inspecting  and  indicating  the  minute 
variations  of  plane  surfaces.  The  rod  of  the  indicator  may  be 
slid  edgewise  in  its  mounting  as  required,  and  it  may  be  reversed 
as  shown  in  the  upper  figure.  The  indicator  consists  of  a  little 
vertically  moving  hardened  steel-plunger,  the  inner  end  of  which 
bears  against  the  short  end  of  the  spring-actuated  lever,  the  long 
end  of  which  is  a  finger  which  traverses  the  graduated  quadrant, 
giving  readings  to  the  thousandths  of  an  inch.  The  mounting 
which  carries  this  indicator  is  bent  upon  itself  so  as  to  form  a 
long  slit  or  opening  and  to  permit  the  piece  to  be  sprung  apart 
by  the  pressure  of  the  horizontal  milled  head-screw  seen  in  the 
upper  figure.  This  screw  is  used  for  giving  minute  movement 
of  the  indicator  when  required  to  bring  the  reading  of  the  figure 
accurately  to  one  of  the  graduation  marks,  or  when  the  indicator 
is  used  in  connection  with  the  scriber,  to  bring  them  both  to  co- 
incident graduation  marks.  The  applications  of  this  instrument 
will  suggest  themselves  to  those  who  are  familiar  with  the  cruder 
instruments  of  the  same  class,  and  which  are  used  so  extensively. 


GAGES  AND   GAGING   SYSTEMS 


INDICATORS  AS  APPLIED  TO  MILLING  MACHINES 


99 


While  the  usefulness  of  the  graduated  multiplying  indicator 
as  applied  to  the  lathe,  planer  and  testing  work  is  pretty  gener- 
ally understood,  there  are  many  other  operations  in  all  depart- 
ments of  metal  manufacture,  where  by  its  use  work  can  be  both 
facilitated  and  improved.  Having  lately  experimented  with 
very  satisfactory  results  for  the  purpose  of  determining  its  actual 
value  in  a  regular  line  of  machine-tool  milling,  we  will  try  and 
describe  a  few  operations  where  it  was  used  to  advantage. 

In  Fig.  97  a  freshly  ground  cutter  is  shown  mounted  on  a 
lathe  mandrel  (previously  tested)  in  a  pair  of  Pratt  &  Whitney 
centers  having  an  indicator  attached,  to  determine  if  (when  re- 


FIG.  97.  —  Testing  Cutter  with  Indicator. 

volving)  all  the  teeth  are  "even"  or  concentric.  This  is  espe- 
cially useful  when  applied  to  machine-relieved  cutters.  Fig.  98 
shows  a  rig  for  holding  the  indicator  while  truing  a  cutter  when 
both  cutter  and  arbor  are  in  place  on  the  machine. 

Arbors  are  ground  from  .003  to  .005  inch  smaller  than  the 
sizes  of  standard  holes  in  cutters,  to  permit  the  shifting  of  the 
cutters  when  truing.  Indicators  having  flat  shanks  or  stems  are 
most  convenient  when  they  are  used  occasionally,  or  on  different 
machines,  as  they  then  can  be  readily  clamped  to  fixtures,  work 
or  table,  and  in  many  positions.  When  they  can  be  suspended 
from  the  overhanging  arm,  as  in  Fig.  99,  or  column,  those  with 
round  shanks  or  stems  are  best. 

Fig.  100  shows  how  single  or  double-ended  facing  and  boring 
cutters  in  boring-bar  are  tested,  both  for  diameter  of  hole  to  be 


IOO 


GAGES   AND   GAGING    SYSTEMS 


bored  and  for  truth,  displacing  the  old  cut-and-dried  method  by 
one  absolutely  certain. 

Anticipating  objections  which  may  be  made  to  having  arbors 
smaller  than  holes  in  cutters  on  account  of  shifting,  we  will  say 
that  with  a  4-pitch  gear  cutter  having  a  hole  .01  inch  larger  than 
arbor,  we  milled  50  inches  of  steel  \  inch  deep  at  a  speed  of  37 
feet  per  minute  and  .098  inch  table  feed  per  revolution;  and 


FIG.  98.  — Truing  Cutter. 

again,  15  inches,  \  inch  deep,  at  a  speed  of  41  feet  and  .150  inch 
feed  per  revolution  without  shifting  the  cutter;  also  the  arbor 
was  not  splined.  This  forces  the  conclusion  that  when  arbor 
collars  are  properly  porportioned  and  in  good  condition,  they 
will  not  slip  unless  abused  or  overloaded;  also  that  keyways,  for 
the  most  part,  are  unnecessary.  Cutters  properly  ground,  run- 
ning true,  with  every  tooth  doing  its  proper  share  of  work,  last 
longer,  do  better  work,  and  can  be  crowded  harder  than  when 
any  of  these  essentials  are  missing.  We  neglected  to  state  that 
in  truing  we  established  a  limit  of  error  of  .002  inch,  though  .001 
inch  is  easily  attainable. 


IOI 


GAGES   AND   GAGING   SYSTEMS 

A  TEST  INDICATOR 

The  drawings,  Figs.  101  to  104,  illustrate  an  indicator  which 
we  designed  and  made.  The  important  feature  of  this  tool  is 
the  dial,  which  though  only  ij  inches  diameter,  gives  room  to 
show  errors  highly  magnified,  the  ratio  being  350  to  i. 

The  graduations  read  in  half  thousandths,  but  quarter-thou- 
sandths or  even  smaller  amounts  can  easily  be  estimated.  The 


FIGS.  99  and  100.  —  Uses  of  Test  Indicator. 

limit  is  ten  one-thousandths,  or  one  turn  of  the  pointer.  When 
in  use  the  plunger  A  touches  the  work  and  any  imperfection  will 
cause  it  to  move  the  lever  B,  which  through  link  C  actuates  the 
gear  segment  D  and  rotates  the  pinion  E  with  the  spindle  carrying 
the  pointer.  The  latter  is  returned  to  zero  by  a  volute  spring  F. 
The  attachment  G  is  used  for  inside  work,  or  for  testing  any 
surface  at  right  angles  to  the  indicator.  The  tool  H  is  used  in 
testing  centers  in  lathe  work  held  on  the  face-plate  or  in  the 
chuck. 


102 


GAGES  AND  GAGING  SYSTEMS 


All  working  parts  are  encased,  and  the  dial  is  with  a  heavy 
watch  crystal,  which  makes  it  dust  proof.  A  watch  crystal  may 
seem  out  of  place  in  a  machinist's  kit,  but  it  is  a  good  thing  to 
have  if  for  no  other  reason  than  that  it  silently  demands  the 
careful  treatment  such  a  tool  deserves. 

This  indicator  is  not  only  adapted  to  lathe  work,  but  is  often 
found  very  useful  when  setting  in  the  shaper  or  the  planer,  and 
especially  in  setting  shaper  vises  perfectly  true. 


FIGS.  101,  102,  103  and  104.  —  Test  Indicator. 

A  TEST  INDICATOR  AND  HOLDER 

Figs.  105  and  106  illustrate  a  test  indicator  which  we  found 
to  be  very  useful.  Fig.  105  shows  the  body  of  the  instrument 
with  the  cover  removed.  The  tool  carries,  as  shown,  a  pointer  A 
which  is  of  tool  steel,  hardened,  ground  and  lapped  to  fit  sleeve  B 
and  bushing  C,  rod  A  being  shouldered  near  D  to  prevent  it  falling 
out  of  the  sleeve.  Member  A  is  of  course  the  "feeler";  C  is  a 
hardened  bushing  which  supports  the  inner  end  of  A;  it  is  beveled 
internally  to  leave  only  about  -^-inch  bearing  and  is  forced  in 
the  tap  hole  in  E  by  screwing  sleeve  B  down  on  top  of  it.  The 
pin  A  after  passing  through  B  and  C  passes  through  a  clearance 
hole  in  E,  where  it  engages  with  the  forked  lever  F  which  works 
on  a  pivot  carried  between  an  adjusting  screw  in  the  body  and  a 


GAGES  AND  GAGING  SYSTEMS 


103 


conical  seat  at  G  in  the  cover  (Fig.  106).  A  silk  thread  fastened 
to  one  of  the  arms  at  the  forked  end  of  the  lever  (the  other  arm 
being  merely  a  stop  for  the  lever)  passes  several  times  around 
drum  H,  thence  through  a  hole  in  the  lower  end  of  the  latter, 
which  is  countersunk  at  one  side  so  that  a  knot  to  fasten  the 
thread  may  be  drawn  into  it. 

At  /  is  shown  a  hair  spring  which  is  driven  on  the  drum  shaft 
and  held  at  /  in  a  drilled  hole  in  the  body  of  the  tool  by  a  small 


FIGS.  105  and  106.  —  Test  Indicator  and  Holder. 

knurled  plug  forced  into  the  hole.  The  hair  spring  keeps  an 
even  tension  on  the  thread  by  pulling  on  the  drum  from  the 
opposite  direction.  On  the  upper  end  of  the  drum  shaft  is  a 
watch  hand  K  which  is  revolved  by  any  movement  of  pin  A  and 
lever  F. 

Fig.  1 06  shows  the  cover  and  the  dial  with  the  watch  hand  at 
zero  on  the  dial.  The  cover  is  a  piece  of  sheet  steel  fastened  to 
the  indicator  body  with  small  machine  screws  and  having  a  hole 
through  it  to  act  as  the  upper  bearing  for  the  drum  shaft.  The 
dial  has  a  beveled  edge  as  represented,  and  is  fastened  in  place 


IO4 


GAGES  AND   GAGING   SYSTEMS 


by  means  of  a  ring  and  two  small  screws.  A  piece  of  photographic 
film  with  the  emulsion  washed  off  is  cut  out  and  laid  on  the 
shoulder  just  above  the  pointer  and  held  in  place  by  a  round 
spring  of  piano  wire  in  the  beveled  seat  L,  thus  effectually  keeping 
the  dial  free  from  dust. 

In  graduating  the  dial  we  fastened  the  disk  in  place  on  the 
cover  of  the  indicator,  then  placed  the  indicator  in  a  tool-holder, 
held  it  in  the  lathe  tool-post  and  brought  the  end  of  A  in  contact 
with  the  face-plate  of  the  lathe,  first,  however,  scribing  a  zero 
line  on  the  dial.  Then  we  forced  the  pointer  against  the  face- 


FiG.  107.  —  Inclinometer  and  Indicator. 

plate  till  the  indicating  hand  was  at  zero.  Next,  we  slipped  a 
piece  of  sheet  metal  .015  inch  thick  under  A  and  scribed  a  Iftie 
where  indicated,  and  so  on. 

INCLINOMETER  AND  INDICATOR 

The  photograph,  Fig.  107,  shows  a  simple  and  useful  tool 
which  we  have  just  made  and  which  can  be  used  as  a  level,  as  an 
indicator,  and  for  getting  the  angle  of  an  inclined  surface.  The 
tool  is  graduated  at  each  side,  one  pointer  serving  for  both  sides, 
as  the  top  part  of  the  pointer,  or  hand,  is  double  and  the  quadrant 
passes  between  the  two  points;  thus  it  can  be  easily  read  from 


GAGES  AND  GAGING  SYSTEMS 


105 


either  side.  The  pointer  is  fastened  to  a  shaft,  the  ends  of  which 
are  pointed;  on  the  bottom  is  fastened  a  weight  which  always 
keeps  the  hand  vertical,  and  when  the  tool  is  placed  upon  a  sur- 
face to  see  if  it  is  level  or  at  an  angle,  the  hand  shows  it  at  once, 
or  rather  after  a  second  or  so,  for  it  vibrates  a  little.  The  test 
indicator  which  we  have  added  to  the  base  has  at  the  end  a 
hardening  wheel;  a  coiled  spring  keeps  the  plunger  away  from 
the  weight  at  the  bottom  of  the  pointer.  When  this  indicator  is 
used  it  is  pushed  against  the  work,  and  the  rod,  pushing  against 
the  weight,  moves  the  hand  in  the  direction  of  O  on  the  quad- 
rant, the  weight  of  the  tool  holding  it.  A  movement  of  .001 


FIG.  1 08.  —  Lathe  Indicator. 

causes  the  hand  to  move  from  one  line  to  the  next.  It  will  be 
observed  in  the  photograph,  that  there  are  pins  or  stops  which 
keep  the  hand  from  striking  against  the  quadrant;  also  a  screw 
to  lock  the  hand  so  that  the  tool  can  be  carried  about. 


A  LATHE  INDICATOR 

The  instrument  shown  in  Figs.  1 08  and  109,  recently  patented 
by  John  C.  Miller,  Bloomfield,  N.  J.,  is  to  be  used  in  connection 
with  a  lathe  or  a  milling  machine  for  setting  the  center  of  the 
work,  or  any  center  punch  mark  on  the  work,  in  line  with 
the  center  of  the  spindle.  The  operation  of  the  device  is 
evident.  The  disk  C  has  a  split  hub  and  a  nut  by  which  it  is 
clamped  anywhere  on  the  sleeve  F.  The  center  in  the  closed 


io6 


GAGES  AND  GAGING   SYSTEMS 


end  of  this  sleeve  is  placed  on  the  center  of  the  machine  spindle, 
and  the  center  on  the  end  of  G  is  placed  in  the  center  of  the  piece 
of  work  to  be  located,  the  spring  acting  to  press  both  centers 
with  sufficient  force  to  hold  the  instrument  securely.  Near  the 
periphery  of  the  disk  is  a  micrometrically  adjusted  pointer,  and 
by  turning  the  instrument  around  the  contact  of  this  pointer 
with  the  face-plate  will  indicate  in  which  direction  the  work 
requires  to  be  moved  to  correct  setting.  Any  desirable  limit  of 
precision  may  be  observed  in  the  micrometer,  and  the  work  may 
be  set  without  the  present  difficulty. 


FIG.  109.  —  Lathe  Indicator. 

A  TEST  INDICATOR 

As  tool-makers  are  always  interested  in  seeing  something  new, 
especially  if  it  is  a  good  tool  to  add  to  their  collection  in  the 
tool  chest,  the  following  will  be  of  interest: 

The  photograph,  Fig.  no,  shows  a  test  indicator  which  is  all 
right.  As  is  plainly  shown,  it  will  go  where  any  lathe,  shaper  or 
planer  tool  will  go,  or  it  can  be  used  in  the  milling  machine,  as 
the  whole  mechanism  is  arranged  within  the  stock. 

We  find  it  sensitive  to  1-20000  part  of  an  inch  on  smooth 
work  revolving  in  the  lathe.  This  seems  rather  fine,  but  this 
error  can  be  easily  detected  by  closely  observing  the  pointer. 

As  will  be  noticed,  the  lever  system  is  arranged  sidewise,  so 
as  not  to  weaken  the  section  where  the  tool-post  screw  clamps. 
The  body  is  made  of  a  piece  of  cold  rolled  steel  with  one  end 
turned  down  as  shown.  The  push-pin  is  of  tool-steel,  and  presses 
against  the  main  lever. 


GAGES  AND  GAGING  SYSTEMS 


107 


Spring 


Pivot 


Counter  Sunk  Screw  Bearing 
for  Pivot 


FIG.  no.  —  Test  Indicator. 


THE  USE  OF  TEST  INDICATORS  FOR  TESTING  WORK 

In  Fig.  1 1 1  is  shown  a  method  for  determining  by  the  use  of 
an  indicator  the  variations  in  the  diameter  of  numbers  of  round 
pieces,  or  at  various  points,  longitudinally  or  circumferentially, 


B   V 


FIG.  in.  —  Testing  Round  Pieces. 

of  a  single  piece  or  between  a  number  of  pieces  of  unknown  di- 
ameter and  one  of  known  diameter.  An  indicator  is  fixed  upon 
a  plane  surface  B,  and  the  piece  to  be  tested,  A,  is  rolled  back  and 
forth  between  it,  and  by  contact  with  the  shoe  of  the  indicator 


io8  GAGES  AND  GAGING   SYSTEMS 

spindle  it  causes  the  pointer  to  travel  the  graduated  circle,  pieces 
of  larger  or  smaller  diameter  causing  it  to  be  traveled  a  greater 
or  less  distance,  respectively.  This  rig  is  also  useful  for  com- 
paring two  or  more  portions  of  a  flat  or  square  surface  of  a  num- 
ber of  pieces.  When  testing  a  number  of  pieces  —  round  - 
the  small  collar  at  the  upper  end  of  the  spindle  is  adjusted 
vertically  so  as  to  allow  the  lowest  part  of  the  shoe  to  hang 
slightly  lower  than  when  A  is  in  contact;  otherwise  it  would  be 
necessary  to  raise  the  spindle  each  time  work  was  to  be  inserted. 
The  chief  advantages  of  this  arrangement  are  its  rapidity  and 
also  its  reliability;  so  that  different  persons  are  more  likely  to 
get  similar  results  than  by  using  micrometers,  the  results  from 


FIG.  112.  —  Setting  a  Grinding  Machine. 

which  are  governed  by  variations  in  instruments,  body  heat  and 
personal  temperament. 

In  Fig.  1 12  is  shown  a  method  of  setting  a  grinding  machine 
to  grind  straight  or  to  a  desired  taper  in  thousandths  of  an  inch 
for  any  portion  of  —  or  the  entire  length  —  work  without  stop- 
ping the  machine.  By  depressing  the  indicator  spindle  until 
the  shoe  comes  into  contact  with  work  A,  variations  in  diameter, 
if  any,  are  instantly  shown.  This  can  also  be  used  to  determine 
the  diameter  when  a  number  of  pieces  are  to  be  ground,  and  the 
operator  can  always  instantly  inform  himself  as  to  the  amount 
of  stock  that  is  still  to  be  removed;  also,  before  beginning  to 
grind,  how  much  stock  must  necessarily  be  removed  to  make  a 
piece  round,  if  it  should  not  run  true,  or,  in  shop  language,  to 
"see  if  it  will  true  up/'  B  is  the  wheel,  H  the  hood  over  the 
wheel  to  which  the  indicator  is  affixed,  and  P  the  swiveling  plate 
carrying  head  and  tail  stocks. 


GAGES  AND  GAGING  SYSTEMS 


109 


In  Fig.  113  we  show  a  straightening  press  with  centers,  at- 
tached to  which  is  an  indicator  /  secured  by  an  L-clamp  D.  Where 
this  device  was  employed,  as  a  great  deal  of  work  to  be  ground 
was  turned  on  screw  machines  and  centered  afterwards,  with  an 
allowance  of  only  .003  to  .005  inch  for  grinding,  and  as  the  grinder 
operators  often  found  it  impossible  to  judge  before  beginning 
to  grind  whether  pieces  ran  true  enough  to  grind  all  around,  it 
was  necessary  to  have  some  means  by  which  this  point  could  be 
determined  quickly.  The  center  stocks  supporting  the  blocks 
and  bar  can  be  moved  independently,  and  the  center  stocks  can, 
if  desired,  be  moved  to  the  right  or  the  left  end  of  the  bar,  so  that 


FIG.  113.  —  Straightening  Press. 

any  portion  of  any  piece  can  be  tested.  The  addition  of  the 
indicator  to  the  press  does  not  decrease  its  efficiency  as  a  straight- 
ening press  but  rather  increases  it. 

THE  R.  R.  UNIVERSAL  TEST  INDICATOR  AND  MIGHT  GAGE 

The  illustration,  Fig.  1 14,  shows  the  Roach  &  Ridlon  tools, 
which  consist  of  the  indicator  attached  to  the  rod  by  a  swiveling 
clamp;  a  plunger  for  aligning  jig  and  die  work;  a  small  button  to 
take  the  place  of  the  ball  on  the  indicator  when  the  tool  is  used 
in  the  drill  press  aligning  jig  and  die  work,  and  the  case-hardened 
tool-holder  which  can  be  used  as  a  boring  tool-holder  when  not 
in  use  in  connection  with  the  indicator.  The  tool  is  compact 
and  neat  in  appearance.  It  is  graduated  to  read  to  thousandths 
of  an  inch. 


I  IO 


GAGES  AND  GAGING  SYSTEMS 


FIG.  114.  —  Universal  Indicator. 


GAGES  AND  GAGING  SYSTEMS 


in 


SCALE  AND  VERNIER  FOR  FINE  ADJUSTMENT  OF  THE  MILLING 

MACHINE  TABLE 

Referring  to  the  use  of  the  scale  and  vernier  of  a  vernier 
caliper  for  making  accurate  adjustments  of  the  milling  machine 
table,  the  Brown  &  Sharpe  Manufacturing  Company  make  a 
special  scale  and  vernier  which  they  supply  for  this  purpose, 
and  which  we  illustrate  herewith  in  Fig.  115.  The  scale  is  24 
inches  long,  and  the  vernier  reads  to  thousandths.  The  scale 
is  mounted  by  screws  having  T-shaped  nuts  to  enter  the  trip- 
dog  slot  of  the  table,  and  the  vernier  is  attached  to  the  front  of 
the  saddle  of  the  machine.  In  the  illustration  a  shows  the 


FIG.  115.  —  Vernier  Adjustment. 

clamp  screw  for  the  vernier  and  b  an  adjusting  screw  by  which 
the  zero  is  adjusted. 

In  the  engraving  the  finer  divisions  of  the  scale  are  omitted. 

UNIVERSAL  SURFACE  GAGE  WITH  MICROMETER  ADJUSTMENT 

The  general  principle  of  this  gage  can  be  seen  at  a  glance  in 
Fig.  116:  There  is  a  micrometer  adjustment  for  the  needle,  and 
in  tilting  the  spindle,  as  shown  in  the  upper  sketch,  the  level 
comes  in  play  as  before,  and  the  reading  in  thousandths  in  a 
vertical  line  can  be  taken  with  precision ;  or,  if  desired,  the  needle 
can  be  reversed  by  swinging  half  round,  bringing  the  thumb- 
screw at  the  bottom,  when  the  level  comes  in  play  again  the 
same  as  before. 


112 


GAGES  AND   GAGING   SYSTEMS 


FIG.  116.  —  Surface  Gage  with  Micrometer  Attachment. 


SECTION   IV 

THREAD,  WORM,  GEAR  TOOTH,  DEPTH  AND  MISCEL- 
LANEOUS TEST  TOOLS,  THEIR  CONSTRUCTION,  USE 
AND  ADAPTATION. 

A  WORM  AND  SPIRAL  GEAR  TOOTH  GAGE 

IT  is  apparent  from  the  great  interest  manifested  in  all  articles 
published  relating  to  screw-cutting  and  forms  of  teeth  in  spiral 
and  worm  gearing,  that  there  is  a  large  amount  of  this  class  of 
work  being  done  throughout  the  country.  Those  interested  in 
spiral  and  worm  gearing  may  make  use  of  the  thread  tool  gage 
shown  here,  with  which  spiral  and  worm  gears  can  be  figured  out 
near  enough  for  all  practical  purposes. 

From  the  accompanying  illustrations,  Figs.  117  and  118,  it 
will  be  seen  that  there  are  two  scales  used  in  this  gage ;  the  upper 
one  is  the  circular  pitch  scale  A,  graduated  on  the  top  edge  only, 
the  reading  being  taken  from  point  d  directly  above  the  center 
pin.  The  lower  graduation  is  read  by  setting  the  point  /  on  the 
thread  gage  to  correspond  with  the  width  of  the  thread  tool  at 
its  end,  this  being  taken  from  a  table  of  tooth  parts,  such  as  one 
published  by  the  Brown  &  Sharpe  Company. 

Note  that  C  is  adjustable  independent  of  the  main  slide,  but 
is  set  in  correct  relation  to  it,  and,  as  shown  in  Fig.  117,  is  set 
for  the  width  of  a  tool  for  a  rack  of  2  inches  circular  pitch.  The 
protractor  is  for  reading  the  angle  of  the  spiral. 

All  graduations  of  the  straight  scales  read  one  thousandth 
of  an  inch. 

In  figuring  gears,  if  any  two  quantities  are  given  it  will 
determine  the  third  of  the  following:  Circular  thickness  at  pitch 
line,  normal  thickness  at  the  pitch  line,  angle  with  a  perpendicu- 
lar to  the  axis.  As  a  worm  thread  gage  it  will  give  the  correct 
size  at  right  angles  to  the  thread  for  a  thread  tool  for  any  pitch. 

In  operation  the  readings  at  d  and  e  are  made  correct  for  half 

"3 


n4          GAGES  AND  GAGING  SYSTEMS 

the  desired  pitch,  and  at  /  for  the  width  of  a  rack  tooth  of  that 
pitch  —  this  reading  being  taken  from  a  table,  as  already 
explained.  The  protractor  and  scale  are  then  adjusted  to  the 
angle  of  the  thread  or  helix  with  a  perpendicular  to  the  axis,  and 
the  parts  are  then  locked  in  position.  The  whole  slide  is  then 
moved  until  the  corner  of  the  scale  reaches  the  vertical  right- 
angle  stop.  The  tooth  scale  below  now  reads  correctly  for  a 


FIG.  117.  —  Gear  Tooth  Gage. 

thread  of  that  angle  and  pitch,  and  the  tool  can  be  ground  to  fit 
the  jaws  of  the  gage. 

In  Fig.  1 17,  both  the  upper  scales  are  set  to  i  inch  for  i  inch 
thickness  of  tooth,  or  2  inches  circular  pitch.  The  lower  scale  is 
set  at  /  for  a  tooth  thickness  of  .62  for  a  rack  tooth.  The  thumb- 
nut  near  the  zero  of  the  protractor  is  next  loosened,  the  protractor 
is  set  to  read  30  and  the  slide  is  moved  until  the  upper  scale 
strikes  the  stop,  as  in  Fig.  1 18,  and  we  read  at  e,  .87  inch  normal 
thickness  of  thread,  and  at  /  .40  inch  for  the  width  of  the  thread 
tool  at  that  point. 


GAGES  AND  GAGING   SYSTEMS  115 

The  change  in  the  thickness  of  the  teeth  due  to  angularity, 
and  also  tne  distinction  between  pitch  and  lead,  are  seemingly 
not  well  understood  by  a  great  many  draftsmen.  We  have  no- 
ticed the  use  of  the  word  "pitch"  to  refer  to  size  of  tooth  only, 
and  "lead"  to  express  distance  traveled  in  one  revolution  only. 
While  this  has  been  thrashed  out  a  great  many  times,  it  is  cer- 
tainly not  followed  in  all  drafting  rooms. 

Any  draftsman  who  has  to  do  with  the  reception  of  orders  for 
"hobs"  knows  what  a  mixed-up  muddle  they  are  often  in,  and 
sometimes  four  or  five  letters  have  to  be  written  to  get  the  correct 
sizes. 


FIG.  1 1 8.  — Gear  Tooth  Gage. 

HANDY  THREAD,  WORM  AND  DEPTH  GAGE 

The  following  illustrates  and  describes  a  gage  devised  for 
finding  the  proportions  of  screw  and  worm  threads,  and  the 
tools  for  cutting  them. 

The  United  States  standard  involute  worm  thread  and  the 
Acme  standard  thread  have  a  flat  top  and  bottom,  which  neces- 
sitates grinding  the  thread-cutting  tool  with  a  flat  end  varying 
in  width  with  the  pitch.  Solid  gages  are  on  the  market  for  shap- 
ing such  thread  tools,  but  these  are  limited  to  a  few  common 
pitches,  whereas  odd  or  fractional  pitches  are  very  often  required. 
The  gage  in  Figs.  1 19  and  120  has  an  opening  on  one  side  between 
the  jaws  B  B  of  an  angle  of  60  degrees  for  the  United  States 


i6 


GAGES  AND  GAGING   SYSTEMS 


standard  form  of  thread.  On  the  other  is  an  opening  of  29  de- 
grees for  the  involute  worm  thread  or  rack  cutter,  and  also  for 
the  Acme  thread,  which  is  at  the  same  angle  as  the  worm  thread 
or  rack  tooth.  When  closed  the  angular  sides  of  the  openings 


NO.  OF  THD.PERIN. 
DEPTH=.5-rTHOS.PER  IN +  .01 

U.S.  STANDARD. 
WIDTH  =  PITCH -r  8 
DEPTH  =  PITCH  X.65 

INVOLUTE  WORM  THREADS. 
WIDTH  =  CIRCULAR  PITCH  X  .31 
DEPTH  =  CIRCULAR  PITCH  X  .  6866 
WIDTH  =  .  974  ^  DIAMETRAL  PITCH 
DEPTH  =  2. 157  4-  DIAMETRAL  PITCH 


OPEN 


FIG.  119.  —  Thread  Gage. 

meet,  forming  a  sharp  V,  and  the  measuring  points  A  A  measure 
exactly  .500  inch,  or  \  inch,  when  closed.  When  measuring  point 
caliper  i  inch  apart,  the  tail  end  E  of  the  slide  C  is  just  flush 
with  end  of  gage.  The  formulas  stamped  on  the  sides  of  the 
gage  are  always  handy. 


i 


CLOSED 
FIG.   120.  —  Thread  Gage. 

In  using  the  gage  the  proper  width  of  point  of  tool  is  figured 
out  by  the  formula  and  added  to  .500  inch.  The  gage  is  then 
set  to  the  actual  width  of  tool  plus  .500  inch  by  a  common 
micrometer  caliper,  as  shown  in  Fig.  119.  Proceed  in  the  same 
way  for  depth,  except  to  subtract  the  actual  depth  of  the 
thread  from  one  inch,  and  set  the  gage  by  the  caliper  as  before. 


GAGES  AND   GAGING   SYSTEMS  117 

The  following  are  some  of  the  actual  jobs  done: 

A  hob  and  worm  were  to  be  made  3^  threads  per  inch: 

3J  thread  per  inch  =          =  y\  pitch;  .3"  x  .31  =  .093'"  =  width 

point  of  tool. 

.093  4-  .500  =  .593",  setting  of  gage. 
3"  x  .6866  =  .206",    depth    of    thread,     i.ooo  -  .206  =  .794"  = 

'•       setting  of  gage  for  depth. 

A  rack  cutter  was  used  to  be  shaped  up  of  .4o8-inch  linear 
pitch,  to  work  with  a  spiral  gear  (Seller's  motion): 
.408"  x.  3  1  =  width   of   point   of   milling   cutter  +  .500    inch  = 

setting  of  gage. 
.408"  x  .6866  =  depth  of  rack  tooth,     i"  -  (.408  x  .6866)  =  set- 

ting of  depth. 

A    single-thread    screw  was    to    be   made   of   -j^-inch    lead, 
Acme  standard  form  of  thread: 


Ty  lead  =  2f  thread  per  inch  =   --~  ==  .0052  =  width  of  tool. 

Depth  of  thread  =    '—  +  .01. 

The  gage  shown  in  Figs.  119  and  120  is  made  in  the  same 
manner  as  a  common  caliper  gage;  Fig.  121  shows  a  simpler  form 
of  this  gage.  A  piece  of  sheet  steel  A  is  offset  the  thickness  of 
the  stock  as  at  D.  A  cut  is  made  in  the  offset  portion  of  A  for 
B  to  slide  in.  A  piece  C  is  riveted  to  A  to  keep  the  slide  from 
coming  away  from  A.  A  slot  is  cut  in  A  for  the  tightening  screw 
to  slide  in.  We  think  it  is  preferable  to  have  the  tail  end  of  the 
slide  square,  as  shown  in  Fig.  121,  and  not  pointed  as  in  Figs. 
119  and  120.  Then  when  the  gage  is  set  for  depth,  an  ordinary 
depth  gage  may  be  set  for  the  thread  gage  and  used  for  measuring 
the  depth  of  thread. 

GERMAN  THREAD  GAGES 

It  is  the  custom  in  a  German  shop  to  make  the  form  of  the 
thread  on  worms  and  spindles  according  to  gage  like  that  shown 
in  Fig.  122,  and  this  is  the  practice  all  over  Germany;  but  as  no 
one  is  able  to  insert  the  gage  parallel  to  the  axis  of  the  screw,  it 


ii8  GAGES  AND  GAGING   SYSTEMS 

is  evident  that  the  form  of  the  thread  becomes  wrong,  because 
the  shape  of  the  thread  ought  to  be  parallel  with  that  of  the  axis 
of  the  screw.  The  resulting  error  grows  with  the  angle  of  the 
thread. 


FIG.  121.  —  Thread  Gage. 


In  Figs.   123  and  124  we  show  how  to  measure  the  thread 
correctly  on  one  line  and  in  correct  position  with  the  radial  line 


Gage  for  Shape  of  Tool. 


Gage  for  Shape  of 
Thread  Recess 


FIG.  122.  —  German  Thread  Gage. 

parallel  and  vertical  to  the  axis  of  the  spindle.  The  sketch  is 
self-explanatory,  the  main  part  being  the  two-lipped  cone  of  29 
degrees  which  is  moved  in  the  direction  of  its  own  axis,  guided 
by  its  cylindrical  shank.  The  whole  piece  is  finished  by  grinding 


GAGES  AND  GAGING   SYSTEMS 


119 


and  by  preventing  from  turning  by  a  dog.     The  two-lipped  cone 
may  be  reground  when  worn. 

The   best   results   in   manufacturing  will   be   obtained   when 
both  gage  and  tool  are  of  the  same  character,  and  we  therefore 


FIG.  123.  —  German  Thread  Gage. 

purpose  making  the  finishing  tool  similar  to  the  cone  gage.  This 
tool  is  to  be  clamped  in  a  tool-holder,  which  will  fix  it  in  correct 
position,  one  of  the  lips  being  used  as  a  scraping  tool  for  turning 


FIG.  124.  —  German  Thread  Gage. 


the  right-hand  side  of  the  thread  in  one  direction,  and  the  other 
lip  being  used  for  shaping  the  other  side  of  the  lathe  running  in 
the  other  direction. 

Some  hints  for  correctly  making  the  "V"  of  the  gage  may 
be  given:  First,  bore  the  hole  for  the  shank  of  the  gage  and  then 


120 


GAGES  AND  GAGING  SYSTEMS 


turn  the  outer  surface;  then  after  roughing  out  the  "V"  clamp 
the  piece  by  the  outer  surface  of  the  boss,  as  shown  in  Fig.  125; 
using  an  index  plate  as  shown,  one  face  of  the  "V"  is  ground. 
Then  turn  the  piece  180  degrees  by  means  of  the  index  plate, 
and  then  with  the  same  position  of  the  grinding  wheel  grind  the 
other  face  of  the  "V." 


A  PISTON-ROD  THREAD  GAGE 

The  gage  shown  in   Fig.   126  consists  of  a  piece  A  made  of 
i  x  |  inch  flat  iron,  with  its  two  ends  bent  up  about  half  an  inch 


FIG.  125.  —  Grinding  Gage. 

and  filed  to  form  two  V  edges,  which  should  be  60  degrees,  or  the 
same  angle  as  the  threads,  in  order  to  fit  fairly  to  the  old  thread. 
The  distance  between  the  two  should  be  about  equal  to  the  length 
of  the  thread  in  the  cross-head,  in  order  that  these  V's  may 
approximately  represent  in  the  gage  the  first  and  the  last  thread 
in  the  cross-head. 

Another  piece  of  the  same  flat  iron  is  bent  up,  as  shown  at  B, 
and  riveted  to  the  middle  of  A,  its  free  end  being  bent  over  and 
brought  into  line  with  the  two  V  edges,  and  at  such  a  distance 
from  them  that  when  a  V  point  is  filed  on  the  free  end  of  B  the 
old  thread  will  slip  in  between  the  three  points.  The  piece  B 
is  finished  by  bending  and  filing  the  point  until  a  good  caliper  fit 


GAGES  AND  GAGING  SYSTEMS 


121 


is  secured,  and  we  now  have  a  gage  which  not  only  gives  us 
diameter  of  the  thread  at  one  point,  but  gives  us  the  effective 
diameter  at  the  points  where  it  is  important  for  us  to  know  it, 
and  also  provides  us  with  means  of  gaging  the  new  thread,  which 
may  or  may  not  be  of  the  exact  pitch  of  the  old  one,  but  which 
if  made  to  this  gage  will  screw  in  every  time  and  make  a  fair  fit, 


V 


FIG.  126.  —  Piston-Rod  Thread  Gage. 

which  is  all  that  the  repair  man  on  piston-rod  threading  expects 
or  desires,  and  in  fact  is  all  that  the  building  did  in  the  first 
place. 

i 


FIG.  127.  —  A  Taper  Gage. 

A  TAPER  GAGE 

The  sketch,  Fig.  127,  shows  a  taper  gage  made  some  time  ago, 
and  it  is  one  of  the  handiest  tools  imaginable.  The  edges  of  this 
tool  must  be  narrow,  say  ^  inch.  The  lower  jaw  slides  up  or 
down  to  adjust  to  the  work;  the  upper  one  swings  on  a  stiff  joint 
C  to  adjust  to  the  taper;  both  jaws  are  locked  with  thumb-screws. 

As  it  is  half  a  foot  from  A  to  B,  the  graduation  is  made  one 
half  size,  J  inch  reads  i  inch  to  the  foot  taper,  making  it  read 
the  same  as  the  lathe  taper  attachment. 


122  GAGES  AND  GAGING   SYSTEMS 

We  will  suppose  that  the  lathe  centers  need  replacing;  set  the 
gage  on  the  old  center,  then  set  the  taper  attachment  the  same  as 
the  gage  to  turn  up  the  new  one. 

The  tool  can  be  easily  made  by  any  machinist  and  will  prove 
a  great  time  and  trouble  saver  in  the  shop. 

MICROMETER  DEPTH  GAGE 

We  show  a  micrometer  depth  gage  which  was  constructed 
some  time  ago,  and  which  has  since  been  in  frequent  use.  It 
is  inexpensive  to  make,  and  seems  to  have  points  of  advantage 
over  some  other  tools  used  for  the  same  purpose.  The  frame 
may  be  a  malleable  iron  casting,  or  may  be  milled  from  soft  steel 
case-hardened,  and  the  base  ground  true. 

.  Fig.  128  is  a  side  elevation,  and  Fig.  129  a  plan  and  partial 
section  on  the  line  M  M,  Fig.  1 28. 


F  C 

FIG.  129.  —  Micrometer  Depth  Gage. 

In  Fig.  128  it  may  be  observed,  first,  that  the  sliding  rod  A 
is  graduated  with  fine  lines  running  entirely  around  and  \  inch 
apart.  Second,  the  sliding  piece  B  can,  by  means  of  the  mi- 
crometer nut  C  and  screw  D,  together  with  the  spring  E,  be  given 
a  movement  on  A  of  J  inch;  third,  an  indicator  point  on  B 
traverses  graduations  on  the  side  of  the  frame.  These  are  .025 
inch  apart,  corresponding  to  one  revolution  of  C.  Fourth,  there 
is  a  line  on  B  where  A  is  exposed,  that  may  be  adjusted  opposite 
any  line  on  A.  Fifth,  one  end  of  A  has  a  large  and  the  other  a 
small  contact  face;  either  end  may  be  used  down.  Sixth,  inserted 
in  the  lower  end  of  D  is  a  small  broad-headed  screw,  forming  a 
shoulder  against  which  B  is  held  by  the  pressure  of  the  spring  E. 
This  shows  better  in  Fig.  130. 

Fig.  131,  which  is  a  plan  of  sliding  piece  B,  shows  the  manner 
in  which  D  is  held  adjusting  in  B.  This  is  similar  to  the  clamping 
device  for  the  anvil  adjustment  on  the  Brown  &  Sharpe  microm- 
eter. The  tapped  hole  for  the  screw  is  counterbored,  as  shown 


GAGES  AND  GAGING   SYSTEMS 


123 


r\ 


-M 


FIG.  128.  —  Micrometer  Depth  Gage. 


124  GAGES  AND   GAGING   SYSTEMS 

by  the  dotted  lines,  and  is  so  situated  that  a  portion  of  the  screw 
head  binds  against  D,  making  a  very  rigid  connection. 

G,  in  Figs.  128,  129  and  132,  is  a  U-shaped  piece  embracing 
By  each  leg  encircling  rod  A,  and  is  provided  with  a  set-screw  to 
tighten  against  B.  This  is  used  to  clamp  B  to  A  when  desired. 

Fig.  129  shows  the  device  for  clamping  rod  A  in  the  frame. 
The  knurled  screw  F  acts  against  a  small  shoe,  the  face  of  which 
conforms  to  the  round  surface  of  A.  On  this  shoe  is  turned  a 
stem  which  is  encircled  by  a  coil  spring,  one  end  of  which  presses 
against  the  screw  F.  This  spring  keeps  a  constant  pressure  of 
the  shoe  against  A,  which  is  quite  important.  In  the  side  of  the 
shoe  can  be  noticed  a  small  pin  inserted,  which  slightly  protrudes 


MS) 


G 

FIGS.  130,  131,  and  132.  —  Details  of  Depth  Gage. 

through  a  slot  in  the  frame.  This  is  to  enable  the  shoe  to  be 
held  back  by  the  thumb-nail  while  A  is  being  reversed. 

Two  methods  of  measuring  depths  with  tool  are  apparent: 
One  is  to  clamp  B  to  A  at  a  suitable  line,  then  operate  by  means 
of  nut  C.  The  contact  is  felt  very  distinctly,  and  the  nut  may 
be  turned  a  little  too  far  and  then  turned  back  lightly  until  it 
stops.  When  used  in  this  way  the  tool  is  very  sensitive.  The 
spring  causes  an  ideal  contact  between  A  and  the  work.  Or  the 
rod  A  may  be  used  independently  and  slid  down  to  contact  and 
tightened  with  knurled  screw  F.  The  nut  C  may  be  adjusted 
till  the  lines  match  and  the  reading  is  taken. 

When  B  is  clamped  to  A  at  a  suitable  line,  the  gage  is  very 
handy  to  apply  to  the  work  as  it  progresses,  when  the  exact 


GAGES  AND  GAGING   SYSTEMS  125 

amount  still  to  be  planed  or  milled  off  can  be  seen  at  a  glance. 
Or  the  micrometer  can  be  set  at  the  proper  reading,  and  the  rod 
used  independently.  Then  the  amount  still  to  be  removed  can 
be  judged  by  noting  the  proximity  of  the  line  on  A  to  that  on  B. 

This  tool  can  be  adjusted  for  wear  at  any  time,  by  setting  a 
flush  end  nut  C  at  zero,  then  loosening  the  binding-screw  in  the 
back  piece  B,  and  turning  with  a  screw-driver  until  the  lines  on 
A  and  B  coincide,  then  resetting  the  binding-screw. 

In  making  the  graduations  on  the  frame  they  should  be  so 
placed  that  the  operator  will  bring  the  indicator  point  practically 
opposite  o  or  .050  inch. 

MAKING  AN  ARMATURE  TEMPLET 

In  making  armature  segment  templets,  a  little  money  spent 
at  the  start  will  prove  a  source  of  great  saving  when  it  comes  to 
handling  the  thousands  of  punchings  when  assembling  the  ma- 
chines; therefore  we  will  describe  in  detail  the  best  practice  and 
the  way  to  go  about  it. 

The  placing  of  the  dovetails  is  one  of  the  essential  points, 
but  the  location  of  the  slots  is  equally  important,  as  when  assem- 
bling the  punchings  in  the  machine  in  any  way  the  slots  must 
line  up.  The  method  we  are  about  to  describe  of  making  these 
templets  is  based  on  a  system  of  reversing  on  six  accurately 
located  pin-holes,  and  not  filing  to  any. lines  but  working  entirely 
to  a  gage  and  plain  external  measurements.  The  pins  for  the 
six  holes  are  T%-  inch  diameter,  but  i  inch  long,  hardened,  ground 
and  lapped,  and  all  exactly  the  same  size.  The  end  driven  into 
the  templet  is  perfectly  flat,  with  only  the  extreme  corner  taken 
off  with  an  oilstone;  the  other  end  is  beveled  off  to  about  T\  inch 
diameter,  so  that,  when  driving,  a  slightly  slanting  blow  will  not 
drive  the  pin  in  crooked. 

We  are  now  ready  to  describe  the  method,  and  will  use  the 
templet  shown  in  Fig.  133  for  reference;  it  is  to  have  36  slots 
and  12  segments  complete  the  circle. 

For  the  templets,  of  which  we  will  make  two  —  an  original 
and  a  duplicate  —  we  will  take  J-inch  sheet  brass,  which  we  will 
hammer  flat  on  a  plate  with  a  mallet.  Then  we  will  lay  the  two 
pieces  one  on  top  of  the  other,  and  in  some  out-of-the-way  place 
near  each  end,  as  a  and  b  in  the  sketch,  we  drill  two  fVinch  h°les 


i26  GAGES  AND  GAGING   SYSTEMS 

for  two  rivets.  We  now  rivet  the  two  plates  together,  and  with 
a  bandsaw  saw  out  approximately  the  radius  and  dovetails  so 
as  to  relieve  some  of  the  strains  before  we  put  any  accuracy  into 
the  templets. 

Now  they  are  put  on  the  radial  planer,  and  the  outside  edge 
planed,  and  the  inside  marked  to  correct  radius,  by  taking  a 
sharp-pointed  side  tool  and  running  in  about  -£$  inch,  with  the 
square  side  towards  the  templet;  this  groove  is  used  as  a  gage  to 
which  it  is  easy  to  file  the  inside.  As  the  templet  is  now  planed 
we  must  next  determine  the  center  distances  of  the  dovetails 
A  B,  which  is  the  most  essential  step  and  the  basis  of  the  whole 
templet. 

About  the  place  we  want  to  locate  the  dovetail  at  A,  we  drill 
and  ream  a  T\-inch  hole  as  shown.  The  location  of  this  hole  is 


FIG.  133.  —  Making  an  Armature  Templet 


not  particular,  only  it  must  be  a  straight,  smooth  hole  through 
both  templets.  Into  the  hole  drive  one  of  the  six  pins  spoken 
of  before. 

Now  measure  the  distance  from  the  outside  planed  edge  to 
the  center  of  the  pin,  which  can  be  done  accurately,  and  subtract 
this  from  the  outside  radius ;  figure  the  chord  from  an  arc  of  that 
radius  having  12  segments  to  the  circle. 

360° 

radius  x  sine  of —       =  \  chord. 

2  x  number  of  segments 

Having  figured  the  length  of  the  chord,  add  .375  =  diameter 
of  bushing  of  jig  shown  in  Fig.  134,  to  the  chord,  and  set  the  jig 
accurately  by  measuring  to  your  figures. 

Next  slip  one  end  of  the  jig  over  that  one  pin  in  the  templet, 
and  place  the  locating  arm  on  the  bushing;  and  adjust  it  so  that 
it  will  just  touch  the  outer  curve  edge;  transfer  the  arm  to  the 
other  bushing,  and  locate  the  jig  and  clamp.  Now  drill  and 


GAGES  AND  GAGING   SYSTEMS  127 

ream  the  pin-hoie  at  B.  Since  the  templet  depends  on  these  two 
pins  as  centers,  there  is  no  chance  for  any  errors  in  the  center 
distance  of  the  resulting  dovetails.  Drill  another  pin-hole  some- 
where near  the  point  C,  and  through  both  templets  by  driving 
out  the  two  rivets.  We  have  now  drilled  three  holes  without 
laying  out;  for  locating  the  fourth  hole,  D,  we  reverse  the  du- 
plicate templet  on  the  line  x  y,  and  drive  in  the  pin  on  the  dove- 
tail, then  line  up  the  planed  edge  with  a  square  to  shut  out  light, 
clamp  the  templet  and  drill  through  the  original,  using  the  drilled 
hole  in  the  duplicate  as  a  jig,  and  vice  versa. 

Now  we  have  the  three  pins  A,  C,  D,  so  reverse  the  duplicate, 
bringing  dovetail  A  under  dovetail  B  of  the  original,  and  using 


o 


1-r.r 


Arm  for  locating  jig 


FIG.  134.  —  Making  an  Armature  Templet. 

the  drilled  holes  in  each  templet  for  a  jig  drilled  through  the 
other  templet. 

We  now  have  all  six  holes  drilled,  the  last  four  in  correct 
relation  in  the  two  accurately  located  dovetail  pin-holes,  which 
we  distanced  by  measuring  machine  measurements;  therefore 
we  have  the  foundation  for  an  accurate  templet,  as  the  rest  of 
the  templet  is  derived  by  reversing  on  the  six  pins. 

Now  upon  the  original  we  will  lay  out  the  dovetails  and  slots 
approximately,  which  is  not  difficult.  Place  a  center  square  on 
the  outer  edge,  put  a  half  pin  in  the  dovetail  pin-hole,  place  the 
blade  of  the  center  square  against  this,  draw  the  radial  line  x  y, 
and  from  this  line  proceed  with  the  laying  out.  The  next  step 
is  to  drill  and  counterbore  out  the  stock  in  the  slots,  after  having 
again  pinned  the  two  templets  together.  There  is  not  much 


128 


GAGES  AND  GAGING  SYSTEMS 


danger  of  springing  the  templet  by  removing  this  stock,  as  a 
rib,  not  shown  in  the  sketch,  is  left  intact  at  the  upper  end. 

A  counterbore  ^  inch  small  is  plenty  small  enough,  as  with 
a  little  care  in  laying  out,  the  slots  will  not  be  out  that  much. 

For  filing  the  slots  and  dovetails,  so  as  to  insure  their  being 
perfectly  straight  and  square,  we  use  the  filing  jig,  Fig.  135.  This 
needs  no  explanation,  except  that  the  two  screws,  E  and  F, 
against  which  the  outer  edge  of  the  work  rests,  are  adjusted  so 
that  the  hardened  steel  plates  on  the  jig  will  always  take  a  posi- 
tion that  will  make  the  sides  of  the  slots  parallel. 

Before  the  filing  place  the  original  templet  on   top  of  the 


Hardened  Steel  Plates, 


© 

/@ 

1      1 

© 

© 

Flat  Spring 

FIG.  135.  —  Making  an  Armature  Templet. 

duplicate  and  drive  in  the  two  dovetail  pins;  and  in  order  to 
make  it  firmer  drive  in  two  more  pins  in  any  of  the  other  two 
holes.  Next  place  the  jig  with  the  hardened  plates  on  one  side 
of  the  slot,  which  is  on  the  radial  line  with  the  dovetail  (slot  No. 
i,  Fig.  133).  Use  the  laying  out  again  only  as  an  approximation, 
and,  to  allow  for  errors,  place  the  jig  about  .010  inch  from  the 
line  representing  the  edge  of  the  slot;  then  clamp  the  jig  by  tight- 
ening the  screw  G  passing  through  the  jaws,  file  the  slot  down  to 
the  hardened  plates  on  the  jig,  and  then  remove  the  latter. 

Now  drive  out  the  pins  and  reverse  the  duplicate  on  the  line 
xy,  which  will  bring  our  filed  side  of  the  duplicate  under  the 
unfiled  side  of  the  original,  and  vice  versa.  Now  by  means  of  a 
straight-edge  set  the  filing  jig  even  with  the  filed  surface,  and  file 


GAGES  AND  GAGING   SYSTEMS  129 

through  the  other  templet;  then  with  a  micrometer  and  inside 
caliper  obtain  the  width  of  the  slot  now  filed.  If  it  measures 
.010  inch  too  small,  place  the  filing  jig  on  again,  and  with  a  .005- 
inch  thickness  gage  and  a  straight-edge  set  the  jig  to  take  off 
.005  inch,  and  then  bring  the  templets  back  to  their  original 
position  and  file  out  the  other  side,  using  the  surface  just  filed 
on  one  templet  as  a  gage  for  setting  the  jig.  Now  this  slot  is 
right  up  to  plug  size  and  reversible.  In  just  exactly  the  same 
way  we  locate  this  we  file  the  dovetail,  only  we  have  a  dovetail 
gage  instead  of  working  to  measurements.  Now  we  have  one 
slot  and  one  dovetail  complete  on  both  templets;  by  simply 
reversing  the  duplicate  we  can  bring  and  finish  slot  and  dovetail 
under  the  unfinished  slots  and  dovetail  of  the  original,  and,  using 
the  former  as  a  guide  to  set  the  filing  jig  to,  we  finish  that  dove- 
tail and  slot.  Now  we  have  two  slots  and  both  dovetails  finished 
and  exactly  reversible  and  all  center  distances  correct. 

Next  comes  the  spacing  of  the  slots:  Since  the  templet  has 
eighteen  slots  between  the  dovetails,  then  there  is  one  slot  just 
half  way  between  the  two  dovetail  slots.  This  slot  is  numbered 
10  on  the  sketch,  and  it  is  a  simple  matter  to  get  it  exactly  in  the 
center  by  simply  using  the  reversing  method  just  described. 
Now  we  have  two  dovetail  slots,  and  this  central  slot  in  both 
templets  complete.  There  is  no  slot  central  between  No.  10  and 
No.  i,  but  we  find  there  is  a  rib;  the  trick  is  to  get  this  rib  just 
the  right  thickness  so  the  rest  of  the  slots  divide  up  evenly.  To 
do  this  proceed  as  follows: 

With  a  scratch  gage  and  the  planed  surface  as  a  guide,  draw 
an  arc  i  inch  from  the  planed  surface  clear  across  the  templet, 
as  shown  at  m  n.  Subtract  this  i  inch  from  the  outside  radius 
and  figure  the  width  of  the  rib  at  its  intersection  with  this  line. 

It  is  plenty  close  enough  to  figure  the  chord  between  the 
centers  of  two  slots  and  subtract  the  width  of  the  slot;  the  re- 
mainder equals  the  thickness  of  the  rib  at  the  intersection  of 
the  line  m  n. 

Make  a  little  snap  gage  of  a  piece  of  metal  exactly  this  figure 
size,  and  file  the  rib  by  the  reversing  method  described  before, 
only  instead  of  reversing  on  pins,  use  two  flat  plugs  in  slots  i 
and  10,  and  a  pair  of  parallel  clamps.  The  ribs  can  be  filed  very 
accurately  to  size,  as  it  has  a  slight  taper,  generally  about  .008 
to  the  inch;  so  if  the  gage  slides  to  within  J  inch  of  the  arc,  there 
is  .001  inch  yet  to  come  off  the  rib. 


130  GAGES  AND  GAGING   SYSTEMS 

When  the  rib  has  the  right  thickness  and  is  reversible,  we 
finish  the  other  side  of  the  slot  by  placing  our  filing  jig  just  the 
right  distance  away  to  make  the  slot  the  right  size. 

We  have  now  slots  5  and  6  finished;  upon  investigation  we 
find  that  in  between  the  slots  i  and  5  is  a  central  slot,  3;  we  get 
this  slot  central  by  reversing,  using  our  flat  plugs  in  holes  i  and 
5.  Slot  No.  8  we  get  in  the  same  way.  Slots  No.  2,  4,  7,  and  9 
we  use  our  little  sheet  metal  snap  gage  again. 

The  slots  from  i  to  10  are  now  finished  and  correct,  and  by 
reversing  these  ten  slots  into  different  positions  and  using  them 
as  gages  to  set  the  gage  to,  we  file  the  incompleted  slots. 

A  templet  made  in  this  manner  is  accurate  in  every  detail, 
can  be  reversed,  and  slots  can  be  shifted  in  any  way,  and  there 


.1875 


.375 


.125   -'V, 

FIG.  136.  —  A  Locating  Templet. 

will  be  no  greater  error  than  .001  inch  anywhere.  A  templet, 
as  described  above,  is  generally  completed  in  from  forty  to  fifty 
hours. 

Another  advantage  of  duplicate  templets  is,  the  duplicate 
can  be  used  in  making  the  die,  thus  saving  the  original  as  a 
master. 

MAKING  A  TEMPLET  FOR  LOCATING  PARTS 

Piece  A,  Fig.  136,  is  a  templet  that  was  used  on  a  certain 
operation  in  experimenting  to  locate  certain  parts  accurately 
from  a  bushed  .090  hole  in  wing  a,  to  a  .1875  hole  at  right  angles 
to  it.  The  four  holes  in  A  are  body  size  for  10-32  screws,  and 
need  not  be  very  close;  the  piece  that  goes  on  is  located  by  the 
.1875  hole.  Wing  a  was  hardened  up  as  far  as  we  could  without 
hardening  the  thin  part.  There  were  nine  of  these  wanted. 
There  was  nothing  out  of  the  ordinary  in  machining  them  in  the 
soft  stage;  they  were  left  about  .025  inch  large,  and  this  was 
found  more  than  enough  to  finish  >to  size. 


GAGES  AND   GAGING   SYSTEMS  131 

The  first  thing  we  did  was  to  lay  out  the  four  10-32  screw 
holes  fairly  close,  as  we  were  going  to  use  them  to  work  piece  A 
from.  The  hole  for  the  bushing  was  laid  out  approximately 
between  surplus  stock;  this  hole  was  drilled  and  reamed  on  a 
drill  press,  and  the  screw  holes  were  drilled;  then  wing  a  was 
hardened  and  the  hole  lapped  for  the  bushing.  There  were 
fifteen  bushings  made  to  get  what  we  wanted.  In  testing  roughly, 
we  used  an  indicator  test,  and  threw  three  of  them  away  right 
off;  and  with  the  flat  surface  test  with  a  finish  hole  cast  out  two 
more,  which  left  us  one  extra  one.  This  sounds  extravagant,  but 
we  don't  think  it  was  so,  considering  what  would  have  happened 
if  we  had  not  detected  the  poor  ones  in  time.  The  bushings  were 
first  rough  lapped,  then  rough  ground  on  the  outside,  so  they 
would  fit  a  holder  with  a  round  hole  to  clamp  them  while  we 
were  lapping  the  hole.  This  is  good  practice  on  bushings,  for  if 


A  ' 

li 

o-f- 

c 

B     ! 

,0!)0  Plug 
Paper 
FIG.  137.  —  Grinding  Surface  Parallel. 

there  are  any  surface  strains  you  take  them  out,  and  you  hold 
the  work  as  true  as  you  can  get  it. 

After  finishing  and  tapping  the  bushings  home  we  ground 
surface  b  parallel  with  .090  plug  in  Fig.  137,  and  the  proper  dis- 
tance from  it,  using  a  piece  of  gray  iron  milled  out  for  the  wing 
to  enter,  with  a  sixteenth  play  on  the  side.  Piece  B  was  ground 
in  place  on  the  magnetic  chuck,  so  as  to  make  contact  with  the 
other  pole  through  a  loose  piece  of  iron  C,  with  paper  between 
B  and  C.  Piece  d  is  a  block  to  rest  A  on  while  grinding  b,  surface 
C  being  ground  parallel  with  b  by  resting  d  on  the  chuck.  About 
.002  was  left  to  finish  and  correct  errors  liable  to  show  in  the 
squaring-up  test. 

The  work  was  then  taken  to  a  lathe  with  draw-in  chucks. 
Fig.  138  is  a  plan  of  the  face-plate,  with  a  floating  or  false  plate 
attached  with  screws  or  straps.  The  floating  plate  was  faced  off 
true,  and  a  f-inch  hole  drilled  through  to  let  a  pin  held  in  the 


132 


GAGES  AND  GAGING   SYSTEMS 


chuck  and  turned  down  to  .1875  inch  stick  through  far  enough  to 
set  piece  D  properly;  the  required  distance  being  obtained  between 
the  .090  plug  placed  in  D  and  the  .1875  pin  just  turned,  by  using 
a  templet  (shown  by  dotted  lines)  of  the  right  thickness  to  go 
between  them.  The  wing  a  (Fig.  136)  was  set  approximately 
central  with  the  .1875  hole  with  an  adjusting  screw,  tapped 
through  one  side  of  piece  D,  as  in  Fig.  139.  In  setting  wing  a, 
we  used  a  line  drawn  across  surface  C  (Fig.  137)  central  with  the 
wing;  then  with  a  fine  point  set  central,  and  turning  the  spindle 
half  way  around,  we  set  the  setting  piece.  Piece  D  once  set  was 


0  ,^XN  \ 


FIG.  138.  —  Work  Located  in  Lathe. 

not  disturbed.  We  had  to  move  the  adjusting  screw  to  keep 
within  our  surplus  stock.  Using  a  light  strap  to  hold  A  up 
against  the  adjusting  screw  point,  with  the  .090  plug  in  A  and 
D,  we  drilled  and  bored  the  holes  to  size. 

Piece  D  was  finished  the  right  distance  from  the  bottom  up 
to  the  plug  .090,  and  used  as  a  gage  to  test  A  when  grinding 
surface  b,  Fig.  137;  it  was  made  of  gray  iron,  and  the  .090  holes 
were  not  bushed. 

Block  E,  Fig.  140,  is  gray  iron,  with  face  e  square  with  the 
bottom.  The  channel  is  the  right  hight  to  allow  the  .090  hole 
to  be  squared  up  by  using  a  plug  about  i|  inches  long,  and 
tapping  A  up  or  down  until  it  shuts  out  light  in  any  of  the  three 


GAGES  AND  GAGING   SYSTEMS 


133 


positions  possible  when  on  grinding  block  F.  We  used  6-32 
machine  screws  to  attach  piece  A  to  block  F,  and  after  it  was 
tapped  square  with  E  ground  surface  /;  and  then  turned  the 
piece  over  on  the  other  face,  squared  the  plug  and  ground  surface 


E 

) 

/f 

._  " 

i 

^0^ 

©         © 

I 

• 

X 
F 

Poin«  of  Screw 


FIGS.  139  and  140.  —  Details  of  Templet  Making. 

g.  Surfaces  /  and  g  at  this  stage  are  parallel,  but  unequal  dis- 
tances from  the  center  of  the  .1875  hole.  Angle  G,  Fig.  141,  is 
what  we  use  for  measuring  from  a  plug  up  to  a  narrow  edge. 
Piece  A  is  shown  in  position  to  be  measured  over  points  marked 
a  with  a  micrometer.  The  angle  G  is  hardened  steel,  ground 


FIG.  141.  — Details  of  Templet  Making. 

and  lapped  and  assembled  as  shown.  After  measuring  these 
pieces,  we  tested  them  by  putting  them  on  a  plug,  and  seeing 
then  if  they  would  reverse  without  the  edges  falling  or  rising. 
Wing  a,  Fig.  136,  was  ground  roughly,  leaving  .0005  on  a  side; 
then  a  finishing  cut  of  .0003  was  taken,  which  left  .0002  to  lap 
—  which  is  all  we  want  on  a  piece  like  this.  Surfaces  /  and  g, 


134  GAGES  AND  GAGING   SYSTEMS 

Fig.  140,  rested  on  a  chuck,  and  surfaces  b  and  c  between  two 
square  parallels  when  grinding  wing  a. 

The  work  was  tested  at  every  stage  in  making  these  templets 
in  this  way. 


FIG.  142.  —  Lathe  Bed. 

TEMPLETS  FOR  PLANING  A  LATHE  BED 

A  templet  or  gage  is  first  made  to  prove  and  secondly  to  bring 
work  to  a  standard.  The  manner  in  which  these  gages  are  made 
often  causes  a  great  difference  in  the  time  consumed  in  fitting. 

The  superintendent  was  a  good  mechanic  and  a  nice  man  to 
work  for,  but  the  shop  was  new,  and  he  had  much  to  contend 
with.  When  the  better  templets  were  shown  to  him,  he  at  once 
allowed  them  to  be  made.  In  Fig.  142  is  shown  the  end  view  of 
the  lathe  bed,  and  in  Fig.  143  the  templet  first  made.  Tnis  was 
required  to  fit  the  V's  and  the  flats  at  the  same  time. 


O  Q 


FIG.  143.  —  Lathe  Bed  Templet. 

The  body  of  this  templet  was  made  of  i  x  2  inch  machine 
steel,  with  V's  cut  in  J-inch  tool  steel  plates.  One  inch  round 
stock  was  turned  down  on  the  ends  and  set  in  to  give  the  hight 
of  the  flat  bearings,  as  shown. 

In  using  this  templet  it  was  necessary  on  account  of  its  nar- 
row bearings  to  use  a  square  to  line  it  up  across  the  bed,  and 
also  vertically.  It  was  a  very  slow  job  of  cut  and  try,  until  the 


GAGES  AND  GAGING   SYSTEMS  135 

templets,  Figs.  144  and  145,  were  made.  After  the  bed  was 
roughed  out,  the  proper  distance  from  the  first  side  of  one  V  to  the 
first  side  of  the  other  was  obtained  by  the  use  of  the  half  templet, 
Fig.  144,  then  the  other  two  sides  of  the  V's  were  finished  until 
the  whole  templet,  Fig.  145,  rubbed  chalk  marks  off  the  four 
sides  of  the  Vs. 

The  flat  bearings  were  finished  last.  The  hardened  steel 
plugs  A  A  in  templet,  Fig.  145,  were  fitted  so  as  to  hold  paper 
between  their  faces  and  the.  job.  The  templet  for  planing  the 
tool  carriage  was  of  course  just  the  reverse  to  Fig.  145.  The 
saving  of  time  in  using  the  last  templet  was  over  3  to  i. 


|/ 


FIGS.  144  and  145.  —  Lathe  Bed  Templet. 

A  PERMANENT  SNAP  GAGE 

The  snap  gage  shown  in  Figs.  146  and  147  consists  of  jaws 
B  B  and  center  piece  A,  the  latter  being  exact  width  of  dimension 
desired.  After  pieces  B  B  have  been  ground  and  lapped,  they 
are  put  together  by  means  of  screws,  as  shown.  Plug  D,  Fig. 
148,  is  a  good  gage  to  test  the  snap  gage  with. 

In  constant  use  a  gage  of  this  kind  will  wear,  especially  if 
used  to  test  round  pieces  such  as  would  naturally  be  turned  and 
twisted  in  the  gage,  and  give  rise  to  hills  and  valleys.  This  may 
be  detected  by  a  plug  gage,  as  shown,  one  of  which  is  the  same 
size  as  the  snap  gage,  and  the  other  end  .001  or  .0005,  or  any  limit 
that  may  be  established,  larger.  When  the  big  end  of  the  plug 
will  enter  the  snap  gage,  it  should  be .  taken  apart,  ground  if 
necessary,  lapped  and  put  together,  when  we  have  again  a  new 
gage  with  a  little  or  no  gage  expense.  One  end  of  the  plug  is 
marked  size  by  S,  the  other  end  limit  by  L. 

This  is  no  doubt  a  very  superior  form  of  gage.  Its  great 
merit  lies  in  the  fact  that  the  more  expensive  piece  A,  which 
determines  the  size,  is  not  subject  to  wear,  while  the  correction 
of  the  gage  .when  worn  does  not  involve  any  expensive  work,  by 
merely  the  resurfacing  of  pieces  B.  The  screws  should  be  a  loose 
fit  in  A,  to  avoid  any  tendency  to  swell  that  piece.  Most  of 


i36 


GAGES  AND  GAGING   SYSTEMS 


these  gages  that  we  have  seen  (and  they  are  the  accepted  form 
of  gage  in  some  leading  and  first-class  works)  have  but  a  single 
end,  two  screws  only  being  used  and  one  end  of  A  being  extended 
beyond  the  jaws  to  form  a  handle,  thus  making  a  gage  which  is 
more  like  the  usual  form.  The  construction  shown  has  the  ad- 
vantage that  at  a  trifling  additional  expense  two  gages  are  made. 
It  would,  however,  be  obviously  impracticable  to  make  these  of 
different  dimensions  to  act  as  limit  gages. 


FIGS.  146,  147,  and  148.  —  Permanent  Snap  Gage. 

ROD  GAGING  FIXTURE 

Having  to  gage  for  length  a  number  of  steel  rods  of  various 
diameters  and  lengths,  and  it  being  necessary  that  there  should 
not  be  more  than  one-thousandth  variation  either  way,  the  gage 
in  Figs.  149  and  150  was  devised  to  detect  the  slightest  inac- 
curacy of  length. 

In  a  gray-iron  base  block  A  were  cut  a  series  of  V-grooves 
of  depths  according  to  the  diameter  of  the  style  of  shaft  for  which 
each  was  intended.  At  one  end  of  A  a  groove  was  cut  a  slight 


GAGES  AND  GAGING   SYSTEMS 


137 


angle;  running  freely  in  this  groove  was  a  steel  strip  B,  screwed 
to  which  was  a  steel  block  C,  having  a  hardened  and  ground  face, 
which  was  square  with  the  grooves  in  the  base.  At  one  end  of 
C  were  placed  graduations,  and  also  on  the  slide  plate  D.  At 
the  other  end  of  the  block  A  was  fitted  a  hardened  and  ground 
steel  block  E,  which  received  one  end  of  the  shafts  and  was  cut 
away  according  to  the  lengths  of  these.  A  shaft  to  be  gaged 
was  placed  in  the  groove  which  bore  its  number,  and  the  block 
B  advanced  until  the  face  of  C  contacted  with  the  end  of  the 
shaft,  the  vernier  marking  on  the  end  of  the  block  then  showing 
whether  the  shaft  length  was  to  the  required  degree  of  accuracy. 


--10.625    -• 


FIGS.  149  and  150.  —  Rod  Gaging  Fixture. 

A  PLANER  GAGE 

The  sketch,  Fig.  151,  shows  a  gage  which  is  perhaps  a  little 
out  of  the  ordinary;  it  is  used  to  gage  the  width  of  planer  beds, 
the  top  rails  being  planed  to  a  similar  gage,  and  the  object  being 
to  jig  the  side  screw  holes  in  the  top  rail. 

The  main  casting  A  floats  in  the  blocks  B  which  rests  in  the 
V's  of  the  planer  bed.  These  supports  are  about  6  inches  long, 
and  serve  to  keep  the  gage  screw  with  the  tracks. 

C  and  D  are  hardened  and  ground  steel  disks,  held  in  posi- 
tions by  flat-head  screws.  Opposite  these  disks  are  two  holes 
through  the  casting  A,  fitted  with  hardened  bushings  and  plungers 


j38  GAGES  AND  GAGING   SYSTEMS 

E  and  F.  The  outer  end  of  the  plungers  and  bushings  are  ground 
flush  when  the  gage  is  set  to  the  standard  size,  or  22|  inches. 

The  method  of  getting  this  size  may  be  of  interest,  the  avail- 
able tool  being  a  1 2-inch  vernier.  Two  pieces,  G  and  H,  were 
turned  and  fitted  to  a  bushing,  the  ends  square  to  nj  inches, 
and  two  pointed  screws  used  to  draw  the  ends  together,  as  shown. 
This  measuring  rod  was  used  between  the  points  C  and  D  and 
E  and  F,  first  getting  C  and  D  square  with  the  inside  of  the  gage. 

The  general  dimensions  of  the  casting  A  were  as  follows: 
Main  web  and  cross  ribs,  \  inch  thick;  outer  rim,  \  x  i^  inches; 
inner  rim,  f  x  i  \  inches,  except  at  supports,  where  it  is  \  x  2j. 


FlG.  151.  —  Planer  Gage. 

GAGES  FOR  TEXTILE  MACHINE  WORK 

Fig.  1 52  shows  the  gages  used  in  the  manufacture  of  spindles 
for  textile  machinery. 

When  a  drawing  is  received  for  a  new  spindle,  the  first  thing 
done  is  to  make  a  sample,  which  is  used  as  standard  for  all  others 
of  that  kind  made.  Hardened  and  ground  plugs  are  made  for 
the  different  diameters  and  tapers,  and  are  used  to  make  the 
gages  from  and  for  testing  the  gages. 

For  grinding  straight  work  over  4  inches  in  length  ordinary 
yes-and-no  ring  gages  are  used.  The  operator  also  has  a  try- 
gage,  like  A,  made  from  |-inch  stock,  thickened  to  f  inch  at  the 
contact  points.  The  operator  uses  this  gage  without  removing 
.the  work  from  the  machine.  When  this  gage  will  go  over  the 


GAGES  AND  GAGING  SYSTEMS 


139 


work  easily,  the  operator  removes  the  work  from  the  machines 
and  tries  his  yes-and-no  gages,  which  have  a  limit  of  .0015  inch, 
and  he  rarely  has  to  put  the  work  back  in  the  machine.  As  the 
gage  wears  it  is  peened  at  a  to  bring  it  back  to  size. 

At  B  is  a  spindle  on  which  the  taper  has  to  be  ground  very 
accurately,  and  the  gage  has  to  be  a  certain  distance  from  the 


FIG.  152. —  Gages  for  Textile  Machine  Work. 

extreme  point  within  the  limit  of  .01  inch.  Three  gages  are 
used,  C,  D,  and  E.  C  is  the  ring  gage  to  get  the  taper  by,  and 
has  a  step  on  top  .01  inch  high.  D  is  the  spanner  gage  to  get  the 
length  by,  made  from  J-inch  square  stock.  E  is  the  try  gage. 
The  slot  is  cut  in  the  top  so  that  it  will  slip  over  the  center,  so  as 
not  to  back  the  center  off  when  trying  the  gage.  When  the 
operator  rings  up  the  machine  for  grinding  this  taper,  he  first 


140  GAGES  AND  GAGING   SYSTEMS 

grinds  one  spindle  to  size,  and  then  adjusts  the  little  piece  of 
steel  b,  so  that  it  will  just  rub  against  the  side  of  the  rest.  This 
gage  will  then  show  every  time  when  the  work  is  down  to  size. 
In  grinding  each  piece,  he  uses  this  gage,  and  when  he  feels  it 
touch  the  rest  he  removes  the  work  and  tries  his  ring  gage,  and 
then  his  spanner,  which  has  to  touch  on  the  lower  step,  but  not 
on  the  top  one;  anything  between  the  two  is  all  right. 

The  gage  F  is  the  one  used  for  gaging,  our  taper  grinding  up 
to  f  inch  diameter  and  6  inches  long.  When  taper  and  size  are 
correct  the  end  of  the  spindle  will  come  flush  with  the  top  of 
wire  c,  the  top  ring  will  be  flush  with  the  wire  d,  and  the  two 
middle  rings  will  be  flush  with  the  marks  on  this  wire.  For 
small,  accurate  work  this  gage  can  be  recommended.  As  the 
gage  wears,  the  wire  c  can  be  driven  out  and  a  longer  one  inserted, 
and  if  the  holes  do  not  wear  equally,  the  ones  that  wear  least  can 
be  polished  out.  All  of  our  gages  for  lathe  work  up  to  J  inch 
are  made  like  G,  but  with  only  one  hole,  the  roughing  gages  being 
made  with  point  contact  and  the  finishing  with  line  contact,  as 
shown. 

For  gaging  taper  work,  like  H,  on  the  turret  lathe,  we  use  a 
gage  like  /,  and  the  taper  is  determined  by  placing  the  gage  on 
the  work  and  holding  up  to  the  light;  the  size  is  determined  by 
the  gage  touching  both  the  taper  and  the  shoulder  on  work. 
On  lathe  work  above  J  inch  we  use  the  gage  K,  made  from  -fg- 
inch  flat  stock.  For  pointing  to  length  we  use  an  adjustable 
spanner  gage  like  L,  made  from  round  stock. 

These  gages  are  all  easily  and  cheaply  made,  and  fulfil  all  the 
requirements  of  spindle  making,  and  will  perhaps  be  of  use  to 
others. 


SECTION  V 

INSIDE  MICROMETER  CALIPERS  AND  OTHER  GAGES 
FOR  INTERNAL  MEASURING;  THEIR  CONSTRUCTION 
AND  USE. 

MAKING  SMALL  INSIDE  MICROMETER  GAGES 

THERE  are  now  on  the  market  numerous  different  makes  of 
inside  micrometers  and  inside  micrometer  gages,  the  smallest 
measuring  as  small  a  hole  as  2  inches.  Now  all  machinists  know 
that  there  are  more  holes  bored  below  2  inches  in  diameter 
than  over  2  inches.  But  so  far  none  of  our  tool  manufacturers 
has  undertaken  to  fill  the  demand  for  measuring  tools  for  these 
small  diameters,  although  we  all  agree  that  closer  measurements 
can  be  taken  with  an  inside  micrometer  gage  than  with  an  inside 
caliper. 

Tools  of  this  kind  for  small  sizes  can  be  made  cheaply  and 
would  soon  find  a  market.  For  making  a  micrometer  gage  to 
measure  from  £  inch  up,  let  us  take  a  piece  A,  Fig.  153,  of  -^- 
inch  machinery  steel,  put  it  in  the  lathe  with  a  spring  chuck,  center 
it  and  drill  a  hole  \  inch  deep  for  tapping,  with  a  J-inch  tap, 
40  thread.  Then  take  a  wabble  drill,  or  rather  make  it  of  a  piece 
of  Stubbs'  steel;  flatten  and  grind  it  out  of  center.  Drill  with 
this  -fo  inch  deeper,  and  then  tap  it  and  turn  a  short  taper  a  and 
thread  it  with  a  fine  thread,  cut  it  off  ^f  inch  long,  turn  it  around 
in  the  chuck,  and  round  and  polish  the  end  with  a  radius  less  than 
J  inch.  With  a  thin  milling  cutter  split  the  piece  at  a  into  four 
jaws.  Make  a  small  knurled  nut  D  to  fit  at  a  for  closing  the 
jaws.  Case-harden  this  sleeve  on  the  large  end.  Next  cut  the 
same  thread  that  we  have  in  the  sleeve  on  a  J-mch  Stubbs  wire; 
round  one  end  and  cut  it  off  ^f  inch  long.  On  the  round  end  of 
this  screw  B  file  a  head,  as  at  C,  and  harden  this  end. 

For  a  wrench  to  turn  the  screw  make  a  round  disk  E  \\  inches 

141 


142 


GAGES  AND  GAGING   SYSTEMS 


diameter,  ^  inch  thick,  with  a  hole  in  the  center  to  fit  the  end  of 
screw  B,  and  graduate  the  disk  into,  twenty-five  equal  parts  to 
correspond  with  our  40  threads  on  the  screw,  and  thus  read  to 
thousandths  of  an  inch.  Harden  the  disk  around  the  hole.  Next 
make  a  handle  H,  4  to  6  inches  long,  to  hold  the  sleeve  A  when 
measurements  are  taken.  At  F  is  riveted  an  indicator  or  hand 
that  swings  on  the  handle,  and  has  an  edge  that  points  to  the 
thousandths  on  the  disk. 

With  an  outside  micrometer  and  disk  E  for  a  wrench,  we 
turn  screw  B  in  the  sleeve  A,  and  set  it  to  any  size  from  J  to 


FIG.  153.  —  Small  Inside  Micrometer. 

1£  inch,  and  lock  the  screw  by  the  knurled  nut  D.  Or  we  place 
the  pointer  on  the  handle  to  match  at  zero  on  the  disk  when 
screw  is  turned  into  the  sleeve,  and  the  tool  measures  %  inch, 
and  lock  the  handle  with  screw  /. 

We  now  have  a  micrometer  for  inside  measurement  within 
the  limits  of  T3g-  inch.  If  we  make  another  sleeve  A  ^f  inch  long, 
drill  and  tap  as  before  \%  inch  deep,  and  in  this  fit  a  screw  ^f 
inch  long,  and  use  the  same  disk,  handle  and  nut,  we  can  then 
measure  a  hole  from  |£-inch  diameter  to  i  inch,  and  still  with 
T%-  inch  of  screw  left  in  the  sleeve,  giving  it  a  good,  steady  hold 
when  locked  with  the  knurled  nut.  The  next  largest  sleeve 
should  be  §|  inch  deep,  and  a  screw  §|  inch  long,  drilled  and 
tapped  ff  inch  long.  This  would  enable  us  to  measure  from  I 


GAGES 


AND  GAGING   SYSTEMS 


'43 


to  IT\  inches.     And  still  another  sleeve  i^f  inches  long,  with  its 
screw  the  same  length,  would  measure  from  iT9^  to  2f  inches. 

This  makes  four  sleeves,  but  all  being  small  and  made  of  soft 
material  and  case-hardened,  they  could  be  made  at  little  expense 
in  a  screw  machine  even;  the  same  disk  and  handle  and  nut  being 
used  for  them  all,  if  we  wish.  One  advantage  with  them  is  that 
we  can  reach  into  very  deep  holes  and  still  have  a  sensitive  and 
reliable  measuring  tool.  One  disadvantage  is  that  the  screw  is 


FIG.  154.  —  Inside  Micrometer  Assembled. 

exposed  to  dust  and  scratches,  the  same  as  older  styles  of  outside 
micrometers;  but  this  can  be  prevented  by  having  four  or  five 
split  brass  sleeves,  which  are  easily  made  to  slip  over  the  screw 
and  cover  most  of  it. 

AN  INSIDE  MICROMETER 

The  half-tone,  Fig.  1 54,  shows  an  inside  micrometer  assembled. 
Its  capacity  is  from  £  inch  to  3^  inches.  Fig.  155  shows  details. 

The  two  members  D  are  made  of  flat  tool  steel,  .070  inch  thick. 
The  three  holes,  E  F  G,  are  drilled  in  line,  the  distance  from  E 


144 


GAGES  AND   GAGING   SYSTEMS 


to  F  being  twice  the  distance  from  F  to  G.  The  locating  and 
finishing  of  these  holes  must  be  done  with  the  greatest  care,  as 
upon  them  the  accuracy  of  the  tool  is  to  a  great  extent  dependent. 

The  upper  parts  of  the  members  D  are  filed  away,  so  as  to 
leave  G  a  little  more  than  half  a  hole.  The  trunnions  H  of  the 
swivels  A  and  B  fit  in  the  hole  G,  and  the  swivels  A  and  B  cannot 
fall  out  of  G  unless  they  are  swung  around  in  line  with  the  mem- 
bers D. 

The  swivel  A  goes  in  the  left  member  D,  as  shown  in  the  half- 
tone. Its  barrel  is  .250  inch  outside  diameter,  and  is  bored  .172 
inches  —  a  sliding  fit  for  the  end  of  the  micrometer  screw  L. 


C 


FIG.  155.  —  Details  of  Inside  Micrometer. 

The  swivel  A  is  also  provided  with  an  adjusting  screw  I  to  take 
up  wear. 

The  swivel  B  is  bored  .250  inch  —  a  sliding  for  A;  the  rear  end 
of  B  is  threaded  at  /  to  form  a  nut  for  the  micrometer  screw. 
The  outside  is  .310  inch  diameter,  and  is  graduated  as  shown  in 
the  half-tone,  the  inch  spacing  being  of  course  only  ^  inch  apart 
because  of  the  two-to-one  ratio  of  the  legs  D. 

The  thimble  C  is  bored  .310  inch  to  fit  over  B.  It  is  .40  inch 
outside  diameter,  and  is  secured  to  the  micrometer  screw  in  the 
usual  way.  The  micrometer  screw,  .250  inch  diameter,  is 
threaded  forty  threads  per  inch.  The  thimble  is  divided  into 
fifty  spaces  instead  of  twenty-five,  for  the  same  reason  that  the 
inch  graduations  on  B  are  half  an  inch  apart. 


GAGES  AND  GAGING  SYSTEMS 


145 


The  contact  points  of  the  instrument  are  disks  .250  inch 
diameter,  with  rounded  faces.  The  ends  of  the  members  D  are 
counterbored  at  E  to  receive  a  small  projection  on  the  side  of  the 
disk,  which  is  fastened  in  place  by  a  small  machine  screw.  When 
a  disk  becomes  worn,  it  may  be  turned  around  so  as  to  present 
a  new  face  to  the  work.  The  U-shaped  spring  K  keeps  the  end 
of  the  micrometer  screw  L  in  with  the  adjusting  screw  /. 

With   this  rule  measurements  within   .001    of  an    inch  may, 
with  practice,  be  made. 

INSIDE  MICROMETER  CALIPER 

In  Figs.  156  and  157  are  contained  sketches  of  an  inside 
micrometer  caliper  which  is  quite  easy  to  make,  and  is  very  useful 


FIGS.  156  and  157.  —  Inside  Micrometer  for  Shrink  Fits. 

in  making  shrink  fits,  etc.  The  frame  A  is  a  brass  casting  made 
in  the  form  shown  to  allow  a  considerable  adjustment  of  rods  B 
and  also  to  make  a  place  for  the  lock-nut  C.  One  end  of  the 
frame  D  is  drilled  out  with  a  J-inch  drill,  and  tapped  with  a  -f? 
tap  (special).  The  other  end  E  is  drilled  J  inch  to  receive  the 
rods.  The  frame  is  placed  on  centers;  the  end  D  is  turned  to 
|  inch,  and  the  end  E  to  J  inch,  and  is  threaded  and  tapered  as 
per  sketch. 

The  barrel  and  screw  are  made  separately,  the  barrel  being 
shrunk  on  the  screw  at  F.  The  screw  has  40  threads  per  inch, 
and  is  -fa  inch  at  top  and  J  inch  at  the  bottom  of  the  thread. 
The  tap  is  made  to  correspond  with  this,  and  is  also  used  to  tap 
the  lock-nut.  The  barrel  was  graduated  on  a  mandrel  in  the  lathe. 


146 


GAGES  AND  GAGING   SYSTEMS 


using  a  5o-tooth  gear,  and  marking  at  every  second  tooth,  making 
25  divisions.  A  straight  line  is  drawn  on  the  end  of  the  frame 
at  D.  The  screw  is  screwed  into  the  frame  until  the  barrel  is 
within  J  inch  from  the  angle  of  the  frame,  bringing  the  division 
marked  0.25  exactly  on  the  line.  The  frame  can  then  be  gradu- 
ated accurately  by  revolving  the  barrel  and  scribing  at  each 
revolution  until  T5o  is  marked  off.  The  clamping  device  holds 
the  rods  firmly  in  place.  We  have  made  four  of  these  calipers, 


FIG.  158. —  Micrometer  Gage  for  Large  Work. 


which  are  in  daily  use  and  giving  satisfaction.  The  one  we  have 
is  nickel-plated,  which  adds  considerably  to  the  appearance  of 
the  tool.  There  are  six  rods  allowing  measurements  from  10 
inches  to  36  inches. 

MICROMETER  GAGE 

The  gage  shown  in  Fig.  158  is  designed  for  large  wprk,  and 
having  a  graduated  head  is  conveniently  used  in  connection 
with  calipers  when  making  allowance  for  shrink  or  press  fits. 


GAGES  AND  GAGING   SYSTEMS  147 

The  screw  A  is  40  threads  per  inch,  and  its  head  is  slotted  to 
suit  finger  B,  which  is  made  of  thin  spring  steel  and  sweated  in 
the  slot.  The  barrel  C  is  graduated  to  25  divisions  and  slotted, 
as  shown,  so  as  to  form  a  spring  fit  on  screw  A.  The  other  end 
of  this  barrel  has  four  slots,  and  in  connection  with  knurled  nut 
D  holds  the  ^-mch  rod  E  in  place.  F  is  an  extension  barrel 
which  is  screwed  on  the  lower  end  of  barrel  C.  If  a  rod,  as  E, 
is  used  and  it  does  not  pass  through  both  barrels,  C  and  F,  a 
short  T\-inch  rod  is  placed  in  C  to  allow  F  to  clamp  thereon. 
The  nut  D  of  course  fits  the  lower  end  of  F. 

INSIDE  GAGE 

Having  several  gun-metal  castings  to  force  over  gray-iron 
bodies,  we  made  a  gage  similar  to  the  one  shown  in  Fig.  159. 
The  casings,  Fig:  160,  were  bored  \  inch  taper  in  8  or  9  feet,  and 
were  large  enough  in  diameter  to  crawl  through.  We  divided 
the  casing  and  gray-iron  body  into  a  number  of  equal  spaces,  as 
indicated,  set  our  lathe  to  the  required  taper,  and  then  calipered 
the  small  end  of  the  casing  and  turned  the  small  end  of  the  body 
to  suit  that  size.  We  next  calipered  the  casing  at  point  2,  to 
find  the  size  that  the  body  should  be  at  the  corresponding  point, 
and  if  the  taper  body  was  on  the  large  side,  we  tapped  the  handle 
of  the  cross-feed  till  it  was  right;  in  this  manner  we  calipered 
at  the  different  points  to  keep  the  work  to  the  required  taper,  as 
in  the  long  casing  the  accuracy  of  the  taper  hole  bored  could  not 
be  depended  upon.  The  reason  the  casing  was  bored  taper  was 
that  it  could  be  slipped  nearly  half  way  over  the  body  without 
coming  to  a  bearing. 

The  body  of  the  gage  is  made  of  a  piece  of  J-inch  brass  gas 
pipe  (although  it  could  be  made  of  iron  pipe)  about  6  inches 
long.  The  end  A  is  tapped  ij  inches  deep  with  a  ^  tap  to  re- 
ceive a  screw  B,  which  has  a  J-inch  hole  drilled  about  -ft  inch 
from  the  tapered  end  to  admit  a  piece  of  wire  for  adjustment. 
A  TVinch  hole  C  is  drilled  3  inches  from  end  D,  and  a  stop  E 
about  J  inch  long  is  forced  down  tight  in  the  pipe  until  it  is  past 
hole  C,  then  the  side  of  the  hole  is  filed  flat  and  flush  with  the 
stop,  as  shown. 

Both  ends  of  the  pipe  are  threaded  for  a  length  of  J  inch  with 
J-inch  pipe  thread,  and  then  split  on  quarters  with  a  hack-saw 


148 


GAGES  AND  GAGING   SYSTEMS 


to  permit  them  to  be  tightened  up  on  the  extension  rod  F,  and 
the  adjustment  screw  by  the  brass  hexagon  nuts,  which  are 
drilled  out  for  J-inch  pipe  thread. 


Extension  rods  F  are  made  of  J-inch  steel  wire,  and  should 
vary  in  length  by  about  \  inch.  In  calipering  a  hole,  you  insert 
a  rod  in  the  end  of  the  pipe  till  it  reaches  stop  E,  and  clamp  it 
by  its  nut,  then  adjust  screw  B  to  get  the  required  size,  and 
clamp  it  also. 


GAGES  AND  GAGING  SYSTEMS 


149 


INSIDE  MICROMETER 

The  Towndrow  micrometer,  Fig.  161,  measures  from  .995  to 
4  inches,  in  thousandths,  and  consists  of  a  head  cross-wise  to 
receive  a  split  and  internally  thread  bushing,  which  is  clamped 


Gray  Iron  Body 


\ 


1  • 

t  / 

. 

I 

J  , 

! 

•  ; 

, 

'    i 

: 

i     : 

'     ' 

; 

WL 

Gun  Metal  Casing 

FIG.  160 


by  a  small  eyebolt  threaded  to  fit  the  end  of  the  knurled  handle. 
The  bushing  thread  is  40  per  inch,  and  one  end  is  provided  with 
twenty-five  graduations,  so  that  with  one  measuring  point 
screwed  in  tight,  the  other  may  be  turned  by  a  small  knurled 
spanner  to  give  the  desired  setting.  The  measuring  points  are 


FIG.  161.  —  Inside  Micrometer  and   Attachments. 

of  such  length  that  with  the  removable  one  screwed  up  against 
the  one  that  is  fixed,  an  even  inch  setting  results;  the  adjustable 
point  is  then  unscrewed  to  give  intermediate  setting  by  thou- 
sandths. Provision  is  made  in  the  instrument  for  adjusting  for 
wear  on  the  points. 


I5o  GAGES   AND  GAGING   SYSTEMS 

AN  INSIDE  MICROMETER  CALIPER 

We  have  had  occasion  to  bore  holes  in  the  lathe,  which  was 
necessary  in  order  to  make  as  straight  and  as  near  a  certain  size 
as  possible;  and,  as  is  often  the  case,  in  some  of  the  shops  the 
supply  of  reamers  was  jimited,  and  it  required  some  very  careful 
feeling  with  ordinary  spring  calipers  to  reach  the  desired  result. 
Now  there  was  not  then  on  the  market  an  inside  micrometer 
caliper  which  would  caliper  less  than  2  inches,  and  at  the  time 
we  made  the  one  about  to  be  described,  the  one  which  we  could 
get  our  hands  on  would  not  caliper  less  than  2|  inches.  Some  one 
probably  suggests,  "Why  not  use  solid  gages?"  Well,  solid 
gages  are  all  right  for  some  work,  but  the  supply  of  them,  like 
those  of  the  reamers,  was  limited,  and  they  were  not  limit-gages 
either.  This  caliper  is  not  intended  at  a  measuring  instrument, 


FIG.  162.  —  Special  Inside  Micrometer. 

but  is  to  be  used,  in  connection  with  outside  micrometer  caliper, 
for  setting  for  the  required  size,  either  above  or  below,  and  may 
be  readily  adjusted  or  detected  in  thousandths  of  an  inch. 

It  consists  of  frame  a,  Fig.  162,  the  spindle  b,  micrometer 
sleeve  c,  movable  contact  piece  /,  set-screw  g,  friction  i,  and 
friction-spring  /.  All  parts  are  steel  except  friction  piece  i, 
which  is  brass;  and  all  wearing  surfaces  are  hardened.  The  frame 
a  is  in  one  piece,  drilled,  reamed,  and  tapped  to  receive  the  spindle 
b.  The  straight  portion  of  the  spindle  is  made  of  nice  working 
fit  in  the  frame  by  grinding  (after  it  is  hardened)  for  about  ij 
inches  from  the  point.  In  fact,  it  is  necessary,  to  the  proper 
working  of  the  caliper  and  the  fits,  for  all  the  moving  parts  to 
be  made  in  this  manner. 

The  sleeve  c  is  made  a  tight  fit  on  the  end  of  b,  and  has  twenty- 
five  divisions.  The  spindle- is  threaded  twenty-four  per  inch, 
and  the  angle  of  its  point  is  such  that  one  revolution  causes  the 


GAGES  AND  GAGING   SYSTEMS  151 

contact  piece  b  to  move  twenty-five  thousandths  of  an  inch,  and 
has  a  range  of  one-tenth  inch. 

The  contact  piece  d  is  first  turned  to  fit  in  its  proper  place, 
but  the  body  of  it  is  made  considerably  longer  than  necessary. 
A  point  reamer,  the  same  shape  and  size  as  the  point  and  un- 
threaded portion  of  the  spindle,  is  then  inserted,  and  a  conical 
hole  made  in  the  piece  of  such  a  depth  that  the  point  of  the  reamer 
just  comes  through.  It  is  then  cut  in  two,  leaving  a  half  conical 
face  on  d  to  form  a  seat  for  the  point  of  the  spindle  b.  This  method 
avoids  the  necessity  of  making  a  perpendicular  key-seat  in  d,  and 
a  pin  or  key  in  the  frame  to  keep  the  piece  from  turning,  which 
would  be  required  if  the  angular  face  of  d  were  made  flat.  The 
movement  of  d  will  be  uniform  if  the  point  of  the  spindle  is  not 
forced  upon  it  to  a  greater  depth  than  that  to  which  the  conical 
hole  was  reamed. 


SECTION  VI 


HIGHT    AND    VERNIER    GAGES    AND    ATTACHMENTS; 
THEIR  CONSTRUCTION,  VALUE,  AND  USE. 

ATTACHMENTS  FOR  THE  VERNIER  AND  DIAL  TEST  INDICATOR 

AMONG  the  valuable  small  tools  in  general  use  in  machine 
shops  and  manufacturing  machinery  plants,  none  is  higher  up 


•  .3-rM 

^  s     •   n 


FIG.  163.  —  Vernier  Attachments. 

than  the  vernier  gage.  Very  often  such  tools  are  made  still  more 
valuable  by  the  aid  of  some  little  attachment.  Fig.  163  shows 
the  vernier  transformed  into  a  hight  gage.  The  base  is  made  of 
gray  iron,  having  a  slot  cut  near  one  side  so  the  tool  can  be  brought 
nearer  to  the  work  when  locating  a  jig  button.  Having  set  the 
sliding  jaw  of  the  vernier  to  zero,  place  it  in  the  block  or  stand 
and  clamp  it  securely  by  the  jig  A;  place  the  scribing  and  hight 
gage  attachment  B  on  the  sliding  jaw  and  fasten  with  screw  C. 
Setting  the  attachment  down  even  with  the  block  or  surface 
plate  enables  one  to  work  from  the  bottom  of  the  surface  plate 
when  locating  jig  buttons,  laying  out  work,  scribing  lines,  etc. 


GAGES  AND  GAGING  SYSTEMS 


'53 


Having  the  buttons  located  on  the  plate  or  jig,  the  indicator 
is  now  wanted  for  truing  up  for  boring  the  holes.     In   many 


FIG.  164.  —  Dial  Test  Indicator  Attachment. 

instances  the  lathe  is  not  available  or  suitable  to  do  the  work; 
therefore  we  must  use  the  milling  machine  or  the  drill  press. 
In  Figs.  164  and  165  a  dial  test  indicator  (Brown  &  Sharpe)  is 


154  GAGES   AND   GAGING   SYSTEMS 

shown  fastened  to  a  shank  fitting  to  a  drill-press  spindle.  A 
T-slot  is  cut  for  the  bolt  A  for  clamping;  this  slot  also  permits 
adjustment  of  the  indicator.  The  attachment  B  is  now  clamped 
to  the  hub  C  by  screws  D,  and  the  arms  G  are  adjusted,  one  to 
the  button  E  and  the  other  to  the  rod  F.  The  joint  H  is  shown 
in  cross-section  in  the  bottom  view  and  requires  no  further  de- 
scription or  explanation.  When  using  this  device  in  the  drill- 
press  or  milling  machine,  the  spindle  of  course  must  be  turned 
by  hand,  and  the  reading  of  the  dial  noted  while  turning  slowly 
and  adjusting  the  work  until  true. 

This  device  can  also  be  used  in  the  lathe  by  using  a  shank 
fitting  the  tail  stock,  the  arms  G  being  adjusted  to  suit  the  button 


FIG.  165.  —  Dial  Test  Indicator. 

or  the  bored  hole,  as  the  case  may  be.     As  the  work  in  this  case 
revolves,  its  truth  is  readily  ascertained. 

PARALLEL  VERNIER  GAGE 

The  cut,  Fig.  166,  shows  a  parallel  vernier  gage  that  has  proven 
to  be  very  handy  in  measuring  when  lapping  and  milling  snap 
gages;  it  can  also  be  used  as  a  small  hight  gage  to  measure  the 
distance  from  a  shoulder  to  the  base  on  a  planer  or  milling  ma- 
chine job.  After  a  snap  gage  has  been  ground  or  lapped  in  a 
machine  to  within,  say,  .0005  inch,  it  must  be  hand-lapped,  for 
a  slight  tipping  to  one  side  or  the  other  is  bound  to  occur  in  the 
machine,  and  as  a  consequence  the  surface  becomes  belly-shaped. 
The  tool  illustrated  is  used  in  connection  with  the  lapping  in  order 
to  get  perfectly  straight  and  parallel  surfaces.  It  has  a  rise  of 


GAGES  AND  GAGING  SYSTEMS 


'55 


|  inch  in  its  length  from  .600  to  i.ioo  inch,  and  it. may  be  used 
for  any  greater  hight  by  fastening  half-inch  blocks^  on  top  of  the 
slide  with  screws.  If  such  blocks  are  used  they  must  be  hardened, 
ground  and  lapped  true.  The  slide  B  is  made  of  tool  steel  and 
is  composed  of  two  pieces.  The  top  plate  is  hardened  and  ground 
and  soldered  on.  Four  small  screws  hold  gibs  in  position  and 
provide  adjustment;  the  tapered  knurled  screw  C  serves  to  lock 
the  top  slide  at  any  point  on  the  base  A  by  lifting  the  binder  D, 
which  is  slotted  on  the  under  side  to  fit  the  dovetail  on  A.  The 
flat  spring  E  is  placed  in  the  top  of  the  hole  in  B  in  order  to  push 
the  bushing  down  clear  of  the  dovetail,  A,  so  that  the  slide  B 
may  move  freely  when  released.  A  ^-'mch  hardened  sheet 


FIG.  1 66.  — Parallel  Vernier  Gage. 

steel  plate  is  also  soldered  on  to  the  bottom  of  the  base  A,  thus 
forming  hardened  working  surfaces  on  top  and  bottom.  The 
tool  is  ground  square  and  parallel  all  over,  and  the  top  and  bot- 
tom are  lapped,  care  being  taken  to  have  the  sliding  parts  scraped 
straight  in  order  that  the  measurements  will  register  correctly 
for  all  settings. 

When  it  is  finished  and  assembled,  the  graduations  should  be 
marked.  This  can  only  be  done  by  hand.  Mark  the  slide  B  in 
the  center  with  a  zero  line  and  locate  it  at  .600,  .700,  .800,  etc., 
positions  on  the  base  by  using  a  micrometer,  and  mark  each 
position  with  a  line  and  the  proper  figures,  as  shown  in  the  cut. 
Then  divide  each  space  into  ten  equal  parts.  To  make  the 
vernier  the  top  scale  must  be  laid  off  so  that  ten  spaces  cover  the 


156  GAGES  AND  GAGING   SYSTEMS 

distance  of  eleven  on  the  lower  scale,  5$  of  the  divisions  on  the 
lower  scale  being  on  each  side  of  the  zero  line  when  set,  as  shown 
in  the  cut.  The  divisions  on  the  vernier  should  be  numbered 
from  i  to  5  on  the  right-hand  side,  and  from  5  to  9  on  the  left- 
hand  side  of  the  zero  mark.  It  will  thus  read  in  tenths,  hun- 
dredths,  and  thousandths.  The  graduation  of  the  instrument 
is  similar  to  that  of  vernier  calipers,  and  is  read  in  the  same  way; 
but  it  is  much  plainer  on  account  of  the  pieces  being  wider.  In 
the  position  shown  the  gage  reads  .850  inch.  If  one  or  more 
thousandths  is  wanted,  move  the  slide  along  until  i,  2,  3,  etc., 
meet  the  corresponding  lines  on  the  bottom  scale. 

Under  no  circumstances  should  this  tool  be  hardened,  as  it 
will  warp  so  that  it  is  impossible  to  lap  it  straight.  This  is  the 
reason  that  the  hardened  steel  plates  are  soldered  on  top  and 
bottom,  so  as  to  give  it  a  hard  surface  on  the  principal  wearing 
parts. 

HIGHT  GAGE  FOR  TESTING  AND  LAYING  OUT  FINE  WORK 

In  Fig.  167  is  shown  a  tool  constructed  for  laying  out  and 
testing  fine  work.  It  has  a  range  by  thousandths,  from  zero  up 
to  5  inches,  the  adjustments  being  accomplished  by  the  plug 
fitting  the  five  bushed  holes  in  the  beam  slide,  and  the  micrometer 
screw  at  o.  The  holes  serve  to  divide  accurately  the  5  inches 
into  equal  steps,  while  the  screw  and  micrometer  nut  p  give  the 
fractions  of  an  inch  in  thousandths.  The  beam  q  fits  into  base- 
block  e,  and  is  secured  there  by  tapered  dowels.  An  easy  way 
to  obtain  a  rectangular  hole  in  such  a  block  is  to  mill  a  slot  of  the 
desired  width,  starting  at  the  rear  end  of  the  block,  and  then  fit 
a  piece  of  steel,  as  shown  at  s  in  the  rear  part  of  the  slot,  this 
piece  being  secured  in  place  with  dowels.  Also  through  the 
forward  part  of  a  block  there  is  a  slot  which  allows  the  measuring 
or  scribing  jaw  t  to  come  flush  with  the  bottom  of  the  base;  this 
jaw,  as  well  as  the  base  block,  is  hardened  and  accurately  lapped. 
The  knurled  head-screw  u  bears  against  a  flat  spring  which  always 
holds  the  slide  in  position  when  the  hardened  and  lapped  plug  v 
is  withdrawn.  The  micrometer  screw,  which  has  40  threads  per 
inch,  is  splined  and  slides  on  a  key  which  is  inserted  in  the  slide. 
Against  this  key  the  tapered  and  knurled  screw  w  bears,  thus 
locking  the  micrometer  screw  at  any  point.  One  of  the  essential 
points,  when  building  a  tool  of  this  description,  is  not  to  have 


GAGES   AND   GAGING   SYSTEMS 


the  bushing  holes  in  perpendicular  alignment;  in  other  words, 
they  do  not  want  to  be  located  so  that  the  plug  v  can  be  entered 
into  No.  3  holes  in  the  slide,  and  yet  go  in  a  No.  i  or  No.  2  hole 
in  the  beam. 


FIG.  167.  —  Tool  for  Laying  Out  Work. 

The  rectangular  hole  through  the  slide  is  formed  in  the  same 
way  as  the  hole  through  the  base  block  — that  is,  by  milling  a 
slot  and  inserting  a  piece  of  steel  at  the  open  end.  The  microm- 
eter nut  p  is  made  in  two  parts;  the  knurled  and  graduated  ring 
being  a  press  fit  on  a  hardened  and  lapped  nut.  The  advantage 
of  this  construction  is  that  it  allows  the  tool  to  be  correctly 
adjusted  without  much  trouble. 


158  GAGES   AND   GAGING   SYSTEMS 

A  SIX-INCH  HIGHT  GAGE 

The  following  description  pertains  to  the  hight  gage  constructed 
as  shown  complete  in  Fig.  168,  and  in  detail  in  Fig.  169.  It 
has  a  range  by  thousandths,  from  zero  to  6  inches,  is  rigid  and 
accurate,  and  can  be  quickly  set  to  exact  position  by  inserting 
a  plug,  as  shown.  The  set  of  six  independent  holes  through 
both  slide  and  beam  are  fitted  with  hardened  steel  bushings, 
ground  and  lapped  to  fit  the  plug,  which  locates  the  various 
inch  settings. 

The  beam  a, — which  forms  the  main  body  of  the  instrument, 
is  made  of  tool  steel,  and  one  end  is  fitted  to  base  b,  which  is  held 
in  position  by  two  straight  pins.  In  a  gage  of  this  design  we  must 
not  have  the  bushing  holes  in  perpendicular  alignment  so  that 
the  plug  c  will  enter  any  other  hole  than  the  corresponding  hole 
in  slide  d.  The  holes  in  the  beam  are  not  drilled  till  after  the 
gage  is  assembled.  The  base  block  is  made  of  mild  steel  and 
case-hardened,  and  in  the  edge  of  the  block  there  is  a  slot  which 
allows  the  scribing  jaw  to  come  flush  with  the  -  bottom  of  the 
base.  A  hole  is  bored  and  tapped  to  fit  the  rod  e,  and  this  hole 
must  be  parallel  with  the  hole  for  the  beam.  An  easy  way  to 
make  the  rectangular  hole  is  to  mill  a  slot  of  the  desired  width 
for  a  driving  fit  for  the  beam,  starting  at  the  rear  of  the  block, 
and  then  fit  a  piece  of  soft  steel  in  the  rear  of  the  slot.  This 
piece  is  riveted  securely  in  place  with  a  soft  steel  wire,  and  finished 
on  the  outside  to  coniform  to  the  base,  which  is  now  as  good  as 
solid.  The  bottom  of  the  block  is  turned  out  in  the  center  to 
within  |  inch  of  the  edge. 

The  screw  /  is  J  U.  S.  standard  and  cut  twenty  threads  per 
inch;  a  TVinch  hole  is  bored  through  the  center  to  receive  rod  e 
and  is  recessed  in  the  middle  to  give  it  a  free  sliding  fit.  The  upper 
end  of  the  screw  is  turned  to  a  driving  fit  in  the  slide  d,  and 
secured  in  position  with  a  pin.  The  top  of  the  thread  is  turned 
off  .01  inch  to  allow  the  scriber  to  slide  freely  on  the  screw.  The 
nut  h  is  used  for  lowering  and  raising  the  slide,  but  instead  of 
having  the  graduations  placed  directly  upon  it,  the  micrometer 
nut  is  made  in  two  parts;  the  knurled  and  lapped  nut  fits  the 
graduated  ring  i,  being  a  press  fit.  The  advantage  of  this  con- 
struction is  that  it  allows  the  tool  to  be  correctly  adjusted  without 
much  trouble.  The  ring  i  is  graduated  with  fifty  divisions,  each 


© 


Of 


O 


ift  3 


Q 


160  GAGES   AND   GAGING   SYSTEMS 

equaling  a  movement  of  the  scriber  of  .001  inch.  This  ring  may 
be  turned  by  means  of  a  small  spanner  wrench  so  as  to  bring  the 
zero  line  into  correct  position  to  compensate  for  wear.  A  knurled 
locking  nut  is  also  provided  for  holding  the  scriber  in  any  fixed 
position. 

The  scriber  is  of  tool  steel,  hardened  and  lapped  to  a  finished 
surface;  it  should  be  ground  at  an  angle  on  top  when  the  edges 
are  worn.  The  rear  end  is  slotted  to  fit  the  rib  of  the  slide,  and 
provided  with  two  screws  to  compensate  for  wear.  On  the  scriber 
there  are  two  zero  marks,  which  show  at  a  glance  the  measure- 
ments being  taken.  The  slide  is  also  of  tool  steel,  and  at  the  top 
a  hole  is  bored  to  fit  the  end  of  the  screw,  but  not  till  the  rectangu- 
lar opening  is  milled  to  assure  its  being  parallel.  The  rectangular 
opening  through  the  slide  is  made  in  the  same  way  as  that  through 
the  base  by  milling  a  slot  and  riveting  in  a  piece  of  steel  at  the 
open  end.  At  the  front  is  a  rib  for  the  scriber  to  slide  on,  and 
one  side  is  milled  at  an  angle  and  has  graduations  of  .025  inch 
for  a  distance  of  i  inch. 

The  knurled  head  screw  k  bears  against  a  flat  spring,  which 
always  holds  the  slide  in  position  when  the  plug  c  is  withdrawn. 
When  the  tool  is  assembled,  the  scriber  is  set  to  zero  with  the 
standard  length  gages  i,  2,  3  inch,  etc.,  and  fastened  with  the 
knurled  head-screw.  The  holes  are  now  drilled  and  reamed 
through  slide  and  beam  at  the  same  setting;  the  same  operation 
is  performed  with  lapping  after  the  bushings  are  driven  in. 


SECTION   VII 

TRY-SQUARES,  KNIFE-EDGE  SQUARES,  COMBINATION 
SQUARES,  STRAIGHT-EDGE  TEST  AND  SIZING 
BLOCKS,  TOGETHER  WITH  METHODS  FOR  THEIR 
CONSTRUCTION,  TESTING,  USE  AND  ADAPTATION. 

SQUARES  AND  SQUARES 

THERE  is  no  doubt  whatever  that  the  commercial  hardened 
squares  are  used  in  many  shops  wherein  their  blades  are  nearer 
straight  than  anything  else  ever  seen  there.  In  such  shops  these 
squares  are  for  all  practical  purposes  straight  and  true  and  square. 
To  refine  them  still  more,  and  to  charge  the  higher  price  that 
would  thereby  be  made  necessary,  would  obviously  be  a  mistake 
for  such  shops.  It  is  clear  enough,  however,  that  there  is  a  class 
of  work  requiring  greater  refinement;  but  it  by  no  means  follows 
that  it  would  pay  any  manufacturer  to  put  the  finest  and  most 
accurate  squares  upon  the  market.  In  those  shops  where  the 
finest  and  most  accurate  squares  are  needed,  there  are  always 
to  be  found  men  who,  given  the  proper  facilities,  can  make  them. 
In  other  words,  where  the  work  requiring  the  use  of  such  squares 
is  done,  men  must  be  employed  who  are  capable  of  making  the 
squares,  whether  they  actually  do  make  them  or  not;  and  as 
most  of  the  work  of  producing  such  squares  is  necessarily  done 
by  hand  anyway,  there  is  probably  little  chance  of  there  being 
ever  any  great  commercial  demand  for  such  tools.  Therefore 
every  good  mechanic  should  be  interested  in  learning  of  the 
proper  methods  to  use,  and  the  mode  of  procedure  to  be  followed 
when  a  square  that  will  be  "perfect"  is  required  to  be  made. 

How  TO  PRODUCE  A  CORRECT  SQUARE 

It  has  been  claimed  that  to  produce  a  correct  try-square  is 
an  extremely  difficult  jub.  Oftentimes  that  opinion  has  its 
foundation  in  the  comparison  of  many  commercial  squares  with 

161 


162 


GAGES   AND  GAGING   SYSTEMS 


one.  another.  Most  likely  none  of  the  lot  so  examined  are  proper 
tools  as  test-squares.  In  the  case  of  some  workmen  it  is  little 
wonder  that  their  squares  are  not  true  and  square,  from  the  fact 
that  their  association  is  with  files  and  other  tools,  to  say  nothing 
of  the  many  tumbles  they  get  in  their  lifetime. 

In  order  to  construct  a  correct  square,  we  must  have  a  stand- 
ard, by  which  we  may  know  for  a  certainty  when  our  square 
is  truly  square.  Fig.  170  is  a  standard  of  this  kind,  which,  with 
its  mate  or  opposite,  determines  correctness.  A  is  a  base  with  a 
parallel  across  its  center.  At  right  angles  to  this  parallel  piece 
is  a  second  parallel  pivoted  to  A  in  the  center,  and  held  at  each 
end  by  binding-screws  to  A  when  in  exact  position. 


•  FiG.  170.  —  Standard  for  Square  Testing. 

Special  care  must  be  taken  that  these  parallel  pieces  are  made 
true  in  every  way.  Now  it  is  self-evident  that  when  B  is  at. 
right  angles  with  A,  we  have  a  compound  square  made  up  of  four 
right  angles.  To  construct  a  duplicate  to  fit  we  can  follow  out 
the  removal  of  discrepancies  by  eight  changes  of  position  if  we 
use  the  template  shown,  Fig.  171 ;  or  if  we  make  a  template  with 
four  sides,  we  can  obtain  thirty-two  trial  positions  in  the  con- 
struction of  an  external  and  internal  standard  square.  Having 
thus  produced  an  exact  square  gage,  both  external  and  internal, 
we  are  provided  with  a  standard  of  our  own,  and  we  are  not 
dependent  on  that  "other  fellow's"  make  for  a  test-square. 

Fig.  172  illustrates  a  convenient  method  of  constructing  a 
correct  square.  The  base  is  D,  and  is  a  plane  plate.  On  this  is 


GAGES  AND  GAGING  SYSTEMS 


163 


mounted  the  piece  C,  which  has  been  trued  by  the  square,  Fig. 
170.  This  fixture  is  for  the  purpose  of  locating  the  parts  in 
correct  position  while  being  fastened  together  with  taper  pins. 
Now  if  we  want  a  good  job  we  must  have  a  true  taper  reamer  to 
ream  holes  to  be  fitted  with  good  tool  steel  taper  pins  that  fit 


FIG.  171.  —  Template. 


the  holes  exactly.  Press  them  in  — don't  drive  with  a  hammer 
if  you  want  a  fine  job  —  while  the  parts  are  held  rigidly  in  place 
on  the  exact  square  block,  and  the  result  will  be  that  the  larger 
part  of  all  squares  thus  put  together  will  need  no  subsequent 
correction. 


o     o 

o 
o    o 


FIG.  172.  —  Constructing  a  Square. 

First  produce  good  true  beams  and  blades,  square  and  parallel, 
and  then  the  matter  of  holding  them  together  rigidly  is  an  easy 
one  if  we  do  the  job  right,  as  shown.  If  we  hold  the  beam  and 
blade  together  by  sweating  or  solder,  we  must  have  a  fixture  for 
holding  the  parts  square  all  the  same.  If  the  blade  and  beam 
are  held  in  place  by  taper  pins,  as  illustrated,  do  not  rivet  over 


i64 


GAGES  AND  GAGING   SYSTEMS 


the  ends  to  hold  the  pins  in.  That  will  be  wholly  unnecessary 
if  the  pins  fit  well.  When  the  square  is  together,  grind  off  the 
ends  of  pins  neatly  with  the  sides  of  the  beam. 

Fig.  1 73  shows  one  form  of  a  master  square  by  which  all  forms 
of  squares  may  be  tested,  and  in  the  test  the  constant  correctness 
of  it  is  manifest.  The  beam  is  made  of  two  pieces,  N  N,  with 
blocks  O  O  in  each  end.  The  whole  is  carefully  finished  parallel 
and  square.  The  blade  is  also  a  carefully  finished  piece,  and  is 
mortised  into  the  center  of  the  beam.  The  openings  V  V  serve 
to  test  any  square,  the  inside  with  inside,  or  its  outside,  and  by 


io 


FIG.  173.  —  Form  of  Master  Square. 

the  numerous  changes  which  can  be  made  in  trial  an  absolutely 
perfect  square  can  be  produced. 

METHOD  OF  TESTING  AND  ADJUSTING  TRY-SQUARES 

There  are  a  number  of  geometrical  methods  for  laying  out  the 
right  angles  which  give  theoretically  perfect  results,  but  a  geo- 
metrical method  and  a  practical  shop  method  for  producing 
right  angles  are  two  vastly  different  affairs.  Thus,  for  example, 
the  geometrical  conception  of  line  is  length  without  breadth, 
which  is  a  condition  in  working  mechanics  impossible  to  realize 
except  as  the  boundary  of  a  solid. 


GAGES  AND  GAGING  SYSTEMS 


165 


A  solid  or  its  equivalent,  which  will  have  two  boundaries  at 
right  angles  for  testing  or  adjusting  try-squares,  is  ordinarily 
produced  by  a  series  of  tests  for  inaccuracies  with  other  gages  or 
squares  of  more  or  less  truth.  This  may  or  may  not  be  satis- 
factory, the  results  depending  entirely  on  the  skill  and  patience 
of  the  workman. 

Fig.  174  shows  a  method  for  testing  and  adjusting  try-squares 
which  requires  nothing  besides  ordinary  tools  more  than  four 
disks  of  exactly  the  same  size,  but  what  size  is  immaterial,  except 


M 


FIG.  174.  —  Testing  a  Try-Square. 


that  the  disks  should,  of  course,  be  in  proportion  to  the  size  of 
the  square  to  be  tested.  To  obtain  four  disks  of  the  same  size 
is  not  difficult,  that  is  within  the  limits  of,  say,  one  ten-thousandth 
of  an  inch. 

USING  TEST-BLOCKS  IN  PLACE  OF  A  SQUARE 

Figs.  175  and  176  illustrate  two  test-blocks  that  are  used  for 
squares  in  connection  with  a  surface  plate.  A  small  hardened 
surface  plate,  finished  on  both  sides,  is  very  useful  in  making 
various  tests  and  measurements. 


i66 


GAGES  AND  GAGING   SYSTEMS 


Fig.  175  is  simply  a  hardened  cylinder,  counterbored  at  the 
ends  to  allow  the  wheel  to  run  by  in  grinding  the  end  faces.  The 
cylinder  is  ground  perfectly  straight  and  lapped  to  any  exact 
size.  The  ends  are  then  lapped  on  a  surface  block.  In  using 
this  test-block,  place  both  the  block  and  the  article  to  be  tested 
on  the  surface  plate,  and  test  for  light,  or  use  the  rubbing  test. 

Fig.  176  is  the  same  as  Fig.  175,  with  the  addition  of  knife 
straight-edges  on  opposite  sides,  which  makes  of  it  a  double  knife- 
edge  square  to  be  used  with  the  surface  plate.  The  advantage 
of  these  test-blocks  is  the  comparative  ease  with  which  they  are 


FIGS.  175  and  176.  —  Test  Blocks. 

made,  and  the  fact  that  they  can  be  made  accurate  in  any  shop 
that  has  a  good  grinder.  If  the  opposite  sides  are  ground  and 
lapped  parallel,  and  the  ends  squared  at  the  same  time,  the  sides 
must  be  square  with  the  ends,  which  makes  the  test-blocks  accu- 
rate squares. 

SIMPLE  METHOD  FOR  TESTING  A  FLAT  SQUARE 

Fig.  177  shows  a  simple  and  easy  way  of  testing  a  flat  square, 
such  as  a  carpenter's  square,  24  x  16  inches.  A  good  straight-edge 
is  clamped  upon  a  planer  platen  or  a  horizontal  face-plate,  and  one 
edge  of  the  square  is  backed  against  it.  Instead  of  drawing  a 


GAGES  AND  GAGING   SYSTEMS 


167 


line  along  the  edge  a,  use  two  iron  plugs  of  equal  diameter.  They 
happened  in  this  case  to  be  two  inches  thick  and  three  inches 
long.  These  plugs  were  placed  on  the  face-plate  as  shown. 
Guiding  one  edge  of  the  square  against  the  straight-edge,  the 
other  edge  a  was  brought  to  bear  against  the  two  plugs,  and  to 
make  sure  of  their  bearing  or  contact,  the  square  and  plugs  are 
moved  along  together  for  a  short  distance,  the  square  pushing 
the  plug.  Then  the  square  is  backed  and  turned  over  and  brought 
to  approach  the  plugs  from  the  other  side  —  see  dotted  lines  - 
close  enough  to  try  the  touch  at  both  plugs  with  tissue  paper. 
If  there  is  a  slight  difference  in  the  diameters  of  the  plugs,  one 
may  put  one  in  place  of  the  other  and  divide  the  difference. 

Plug 

o 


Straight-edge  clamped  to  plate 


FIG.  177.  —  Testing  a  Flat  Square. 

How  TO  MAKE  A  KNIFE-EDGE  SQUARE 

While  the  purpose  of  the  following  is  to  describe  how  to  make 
a  fine  square,  and  how  it  should  be  used,  it  may  not  be  amiss  to 
say  that  probably  in  no  other  line  of  manufacture  has  the  inter- 
changeable system  been  applied  for  so  long  a  time,  or  brought  to 
as  high  a  state  of  perfection,  as  in  the  casting  of  type  for  printing. 
This  does  not  mean  only  that  the  type  of  any  one  foundry  will 
interchange  with  those  of  any  other.  The  difficulty  of  main- 
taining an  absolute  interchangeability  and  its  practical  necessity 
will  be  readily  understood  if  we  take  a  page  of  this  book  as  an 
illustration.  If  the  body  of  each  type  in  a  line  was  just  .0001 
inch  out  of  square  on  its  lower  side,  we  would  have  a  curved  line; 
if  some  were  out  of  square  at  the  top,  others  at  the  bottom,  and 
still  others  square,  we  would  have  a  zigzag  line.  As  each  body 


1 68 


GAGES   AND   GAGING   SYSTEMS 


type  must  be  firmly  bearing  against  its  neighbors  when  locked  in 
the  form,  we  would  have  a  column  of  dancing  letters  that  would 
drive  the  reader  distracted. 

Fig.  178  represents  a  square  largely  used  in  making  the  parts 
of  the  molds  —  which  are  themselves  interchangeable,  and  are 


FIG.  178.  —  Square  for  Mold  Work. 

used  on  automatic  machines  —  its   precision   block  and  a  lap- 
ping plate. 

In  Fig.  178  the  beam  a  and  the  blade  b  are  held  together  by 
screws  C  as  shown. 


FIG.  179.  —  Rectangular  Prism. 


Fig.  179  is  a  rectangular  prism,  in  which  the  sides  a  and  b  are 
lapped  parallel  and  end  c  perpendicular  to  them.  Necessarily, 
if  c  is  square  with  either  side  it  must  be  so  with  the  other.  All 
parts  should  be  made  from  machine  steel,  deeply  case-hardened, 
and  allowed  to  thoroughly  "work"  before  finishing,  but  will 


GAGES  AND   GAGING   SYSTEMS  169 

require  frequent  correction  as  long  as  used.  On  account  of  its 
extreme  sensitiveness  the  square  is  worthless  without  the  block 
with  which  to  test  and  correct  it.  The  block  is  corrected  by 
micrometer  and  its  square. 

In  Fig.  178  the  space  d  is  left  to  catch  dust  and  ravelings  of 
cloth  that  would  interfere  if  the  corner  were  left  sharp. 

Figs.  1 80  and  181  show  a  lapping  plate  which  consists  of  a 
cast-iron  plate  having  a  rectangular  recess  filled  with  lead  or 


FIG.  180.  —  Lapping  Plate. 

babbitt  metal,  carefully  planed  and  charged  with  flour  of  emery, 
by  means  of  cast-iron  stick  and  water.  There  should  be  a  pair 
of  these  —  for  roughing  and  finishing  —  and  care  must  be  taken 
to  so  use  them  that  the  wear  is  about  uniform.  When  the  lead 
is  poured  the  casting  should  first  be  made  very  hot  to  contract 
with  the  lead  in  cooling. 


u  u 

FIG.  181.  —  Lapping  Plate. 

In  making  the  square  the  beam  and  blade  are  hardened, 
ground  and  lapped;  the  beam  on  one  side,  the  blade  on  two 
adjoining  sides,  and  the  screw  end. 

As  it  is  quite  impossible  to  lap  the  end  of  the  blade  perfectly 
square,  the  corner  e  is  honed  after  assembling  until  it  is  square, 
and  afterwards  corrected  in  the  same  manner  as  needed.  The 
square  should  never  be  taken  apart  for  that  purpose. 

The  length  of  the  beam  is  usually  about  2|  inches,  and  the 
blade  1}  inches.  The  block  is  slightly  larger  than  the  square. 
The  lapping  plate  is  about  10  x  14  inches. 


GAGES   AND   GAGING   SYSTEMS 


With  practice  an  error  of  .0001  inch  can  be  easily  detected, 
and  in  the  work  for  which  they  are  used  the  limit  of  error  is  slightly 
less. 

KNIFE-EDGE  SQUARE  WITH  HANDLE 

It  must  be  admitted  that  a  square  of  such  fineness  as  the 
knife-edge,  if  used  much,  will  naturally  spring  out  of  truth  from 
the  heat  of  the  hand  and  fingers  while  holding  it.  We  have 
used  the  square  shown  in  Fig.  182,  with  a  wooden  handle  fastened 
to  the  beam  of  it.  The  handle  is  also  convenient  for  picking  up 


FIG.  182.  —  Knife-Edge  Square. 

the  square.  The  space  left  for  dust  at  the  vertex  of  Fig.  178  is 
a  .drawback  sometimes,  but  for  certain  work  this  is  the  most  val- 
uable part  of  the  square.  The  square  shown  in  Fig.  182  was 
made  of  tool  steel,  hardened  and  drawn  to  a  light  straw. 

A  SET  OF  KNIFE-EDGE  TOOLS 

Fig.  183  shows  a  knife-edge  bevel;  at  the  top  is  shown  the 
stock.  It  is  one  of  the  handiest  tools  for  use  on  the  surface 
grinder.  It  is  made  of  tool  steel,  hardened  and  ground  all  over. 

Figs.  184  and  185  show  two  knife-edge  straight-edges  A  and 
B;  Fig.  1 86  is  a  test-bar,  Fig.  187  a  knife-edge  square,  and  Fig. 
1 88  a  test-block.  Considerable  trouble  will  be  experienced  in 


GAGES  AND  GAGING  SYSTEMS 


171 


b 


'"     / 


p 

I 


FIG.  187 


FIG.  183 


FIG.  184 


FIG.  185 


FIG.  i 86 


\/ 

H 


;r 

^j 
.*. 


n 

183 


Ji  Round 


Knife-Edge  Tools. 


FIG.  188 


172  GAGES  AND   GAGING   SYSTEMS 

keeping  tools  like  these  true,  especially  in  winter.  The  warmth 
of  the  hand  will  throw  them  out  of  truth.  This  can  be  overcome 
by  putting  in  the  fiber  or  hard  rubber,  as  shown  by  the  dotted 
lines.  These  tools  should  be  kept  in  a  box  with  a  little  oily 
waste  to  prevent  rust. 

A  KNIFE-EDGE  STRAIGHT-EDGE 

Fig.  189  shows  not  a  lethal  weapon,  but  a  knife-edge  straight- 
edge. It  was  made  by  grinding  and  lapping  an  old  flat-ground 
English  razor.  It  remains  true  longer  than  many  bought  straight- 
edges, and  this  quality  may  be  attributed  to  the  long  years  of 


FIG.  189.  —  Knife-Edge   Straight  Edge. 

seasoning  it  underwent  while   in  use  as  a  razor,  previous  to  its 
regeneration  as  an  instrument  of  precision. 

The  handle  protects  the  edge  very  thoroughly.  One  of  the 
washers  has  been  left  off  the  little  pivot  for  the  blade,  so  that 
the  handle  may  be  easily  removed  should  it  be  necessary. 

USES  OF  THE  COMBINATION  SQUARE 

No  doubt  we  all  have  seen  at  times  our  ideas  and  inventions 
improved  upon,  or  used  to  better  advantage  than  we  have  used 
them.  So  the  sketches,  Figs.  190,  191,  and  192  may  convey  some 
new  ideas  in  conjunction  with  the  combination  square.  We 
do  think  it  might  be  of  advantage  to  the  makers  to  offer  an  extra 


GAGES  AND  GAGING  SYSTEMS 


'73 


base  for  a  slight  advance  in  cost.  Fig.  190  shows  the  square  used 
as  a  hight  gage  which  will  go  into  places  that  surface  gage  cannot. 
Fig.  191  shows  it  used  as  an  outside  caliper.  Fig.  192  shows  how 


FIG.  190.  —  Use  of  Combination  Square. 

odd  shapes  may  be  calipered  on  the  outside.  Edward  Etler,  a 
planer  hand  at  the  R.  K.  Le  Blond  shops,  Cincinnati,  Ohio,  is 
responsible  for  these  ingenious  ideas. 


FIG.  191.  —  Use  of  Combination  Square. 

ADJUSTABLE  SIZING  BLOCK 

Fig.  193  shows  a  sizing  block  which  was  made  for  use  on  the 
planer.  The  body  of  the  tool  A  is  made  of  machine  steel.  After 
the  slot  is  cut  in  it  the  machine  steel  piece  B  with  the  foot  C  is 
fitted  to  it,  a  nice  snug  sliding  fit.  The  hole  D  is  then  drilled 
and  tapped  J  inch,  twenty  threads,  and  is  so  located  that  only 


174 


GAGES  AND  GAGING   SYSTEMS 


about  one  fourth  the  circumference  of  the  tap  cuts  into  B.     B  is 
then  removed  and  a  ^-inch  rose  bit  is  run  down  into  the  hole  in 


FIG.  192. — :  Use  of  Combination  Square. 

A,  cutting  the  threads  away.  The  steel  screw,  Fig.  194,  \  inch 
in  diameter,  twenty  threads,  is  then  made.  At  its  lower  end  is 
the  V-groove  F,  into  which  the  screw  E  engages  when  the  tool 


I 


FIGS.  193  and  194.  —  Sizing  Block. 

is  assembled.  A  groove  G  is  milled  in  the  piece  B,  so  that  the 
screw  H  may  hold  B  and  A,  and  allow  it  to  slide  up  and  down 
freely  without  binding  on  the  screw,  Fig.  194.  An  indexing 


GAGES  AND   GAGING   SYSTEMS  175 

point  is  fastened  to  the  top  of  A,  and  reaches  up  to  the  divided 
collar  on  Fig.  194.  The  collar  is  divided  into  fifty  parts,  and  as 
the  screw  is  twenty  threads,  each  division  equals  .001  inch.  The 
face  /  of  body  A  is  graduated  to  twentieths  and  tenths,  which 
may  be  easily  done  if  left  till  the  last  by  using  the  tool  itself 
for  spacing.  The  foot  C  and  the  top  of  the  sliding  block  B  are 
used  for  sizing.  The  capacity  of  the  tool  as  shown  is  from  \  to 
3!  inches  by  thousandths. 

THE  MAKING  OF  A  REAL  SQUARE 

There  are  classes  of  work  for  which  the  commercial  square 
that  can  be  purchased  in  the  tool  store  or  of  the  makers  is  not 
nearly  good  enough;  though  of  course  this  is  not  saying  that  the 
commercial  article  is  not  good  enough  for  the  vast  majority  of 
work,  and  also  a  very  good  value  for  the  price  asked  for  it,  as 
good  indeed  as  could  reasonably  be  expected.  We  all  know  that 
all  our  tools  and  machinery  lack  more  or  less  of  being  absolute 
perfection,  and  it  is  a  part  of  the  business  to  know  when  a  thing 
is  good  enough  for  the  purpose  it  is  designed  for;  or  as  good  as 
people  can  be  induced  to  pay  us  for  making  it. 

Other  things  being  equal,  it  is  perhaps  generally  true  that 
the  harder  the  materials  we  work  with,  the  more  readily  errors 
in  our  work  manifest  themselves.  The  carpenter's  square  does 
not  need  to  be  nearly  so  accurate  as  that  of  the  machinist,  partly 
because  if  the  end  is  not  cut  off  precisely  square  the  relatively 
soft  material  will  yield  sufficiently  when  it  is  forced  to  place,  to 
make  the  joint  good  enough,  and  something  like  the  relative 
difference  between  the  harder  and  the  softer  materials  is  seen 
when  we  compare  un hardened  metals  with  hardened  and  ground 
or  lapped  steel.  For  such  work  the  store  square  even  of  the  very 
best  make  is  sometimes  not  nearly  fine  enough,  and  it  may  be 
useful  if  we  describe  the  methods  that  have  been  followed  in 
making  squares  that  are  much  more  refined  and  which  in  fact 
enable  us  to  produce  work  which  is  so  nearly  square  as  to  make 
it  possible  to  detect  error  in  it  by  the  most  refined  tests  that  can 
be  applied. 

The  best  manufactured  square,  as  shown  in  Fig.  195,  consists 
of  a  stock  a,  which  is  made  of  three  hardened  pieces,  the  central 
portion  b  (corresponding  in  thickness  to  the  blade)  and  the  two 


176 


GAGES   AND   GAGING   SYSTEMS 


outside  pieces  d  d;  these  three  pieces  are  hardened  and  finished 
true  all  over,  sweat  or  soft-soldered  together,  and  finally  riveted 
with  two  or  more  rivets  clear  through. 

To  better  resist  hard  usage  and  prevent  breakage,  the  blade 
is  hardened  only  on  the  edges,  as  shown  by  the  dotted  lines. 
The  blade  is  fastened  into  the  stock  by  sweating  or  soft-soldering, 
and  by  moderately  heating  it  may  easily  be  removed  and  reset 
in  case  of  wear  or  accident. 

In  use,  and  where  the  work  is  not  too  large,  such  a  square  is 
put  upon  the  work  and  held  up  to  a  strong  light  for  inspection. 

Another  method  used,  especially  with  large  work,  is  to  apply 
narrow  strips  of  paper  at  each  of  the  blade  ends  for  contact,  these 


\ 

1 

0 

a 

o 

b 

a 

C 

__ 

FIG.  195.  —  Making  a  Real  Square. 

strips  being  manipulated  by  the  finger,  and  when  they  are  pinched 
or  held  alike,  one  can  be  pretty  sure  the  work  is  very  nearly  like 
the  square.  The  paper  strips  in  connection  with  the  micrometer 
calipers  have  one  advantage  over  the  eye  inspection,  in  that  they 
not  only  tell  us  when  the  work  is  out,  but  very  nearly  how  much, 
which  is  really. what  we  want  to  know.  In  the  "American  Ma- 
chinist," some  years  ago,  was  illustrated  a  square  invented  by 
G.  A.  Bates,  in  which  the  blade  is  pivoted  on  a  projection  of  the 
stock,  and  by  a  system  of  levers  and  a  scale  is  made  to  indicate 
the  truth  or  untruth  of  whatever  it  is  applied  to,  and  which  way 
and  how  much  it  may  be  out.  Just  why  this  square  has  not 
come  into  use  would  be  hard  to  say;  though  it  is  probable  that, 
like  a  great  many  other  things  mechanical,  it  was  born  too  soon. 
For  very  fine  work,  such  as  gages,  instruments  and  some 


GAGES  AND  GAGING  SYSTEMS 


177 


kinds  of  tools,  no  square  with  a  flat-edge  blade  will  answer  the 
purpose,  for  the  simple  reason  that  the  contact  between  the 
work  and  edge  of  the  blade  is  too  broad  and  will  shut  out  light 
when  they  are  not  really  together  at  all;  and  the  paper  strip 
method  would  not  answer,  because  the  paper  is  too  uneven  in 
thickness  and  too  rough  to  give  the  required  accuracy.  And 
besides,  most  work  of  that  character  would  be  too  small  to  handle 
in  that  way;  so  what  are  called  knife-edge  squares  are  used. 
For  some  reason,  probably  because  of  their  necessarily  high  cost, 
this  class  of  square  is  not  listed  in  any  maker's  catalogue.  The 
few  that  are  in  use  have  mostly  been  made  by  the  workmen 
using  them. 


FIG.  196.  —  Making  a  Real  Square. 

A  hardened  steel  square  of  a  size  usually  below  the  3-inch, 
such  as  was  described  above,  is  sometimes  used  as  a  starter. 
The  blade  is  heated  and  taken  out  of  the  stock,  and  this  latter 
is  then  refmished  on  its  two  edges  by  grinding  and  lapping  until 
they  are  flat  and  as  near  perfectly  parallel  to  each  other  as  it  is 
possible  to  get  them,  by  the  use  of  the  micrometer  caliper  or  other 
gaging  device.  The  blade  is  now  taken  in  hand  and  its  inside, 
and  sometimes  its  outside,  edge  beveled  off,  as  shown  at  a  in 
Fig.  196  (enlarged). 

The  sharp  edge  is  slightly  rounded,  like  a  knife-edge  straight- 
edge so  it  will  stand  wear  a  little  better.  It  is  now  put  in  place 
in  the  stock,  care  being  taken  to  have  the  contact  surface  nicely 
tinned  and  all  the  surplus  solder  removed.  They  are  set  by  trying 


i78 


GAGES   AND  GAGING   SYSTEMS 


on  a  block,  preferably  hardened,  and  which  is  as  near  square  as 
it  is  possible  to  make  it,  and  temporarily  held  and  clamped  on 
the  sides  of  the  stock  and  over  the  blade.  It  is  then  heated  to 
melt  the  solder  and  to  secure  the  blade.  On  account  of  the 
heating  necessary  to  melt  the  solder  and  the  disturbing  influence 
of  contraction  and  expansion,  it  will  be  found  very  difficult  to 
get  the  blade  set  even  approximately  right,  and  sometimes  as 


1 

A 

C 

b 

i 

0 

j^ 

,d 

1  1 

1  1 

a 

i  1 

jj 

\ 

.2              gx 

\ 

I 

r 
f- 
t 

i-4 

j 
j 

r. 

3." 

-J 

>f 

T 


FIG.  197. — -Making  a  Real  Square. 


many  as  four  and  five  trials  are  necessary.  After  this  the  hand 
is  resorted  to  in  order  to  get  it  to  the  required  degree  of  accuracy. 

This  difficulty  in  setting  the  blade  has  led  to  several  designs 
in  which  the  blade  is  held  by  pin,  screw,  or  keys,  doing  away 
entirely  with  the  necessity  for  heating.  One  of  this  variety, 
which  has  given  entire  satisfaction,  is  shown  in  Fig.  197. 

Every  piece  in  this  tool  is  hardened,  even  the  screws  and 
pins,  and  it  is  found  that  by  so  doing  they  "stay  put"  for  a  longer 
time. 


GAGES  AND  GAGING  SYSTEMS 


179 


The  stock  a,  in  Fig.  197,  is  made  of  a  single  piece.  The  slot 
which  holds  the  blade  ends  in  a  round  hole  d,  which  serves  the 
double  purpose  of  preventing  fire-cracks  during  hardening,  and 
makes  a  clearance  that  is  useful  while  lapping  out  the  slot;  which 
must  be  done  so  that  it  closely  and  without  shake  fits  the  blade 
which  has  previously  been  finished.  The  stock  and  blade  are 
pivoted  together  and  free  to  turn  on  pin  e,  which  need  not  be 
fitted  with  any  great  accuracy. 

In  the  stock  are  the  two  screws  /,  and  above  them  the  two 
loose  drill-rod  pins  g,  all  shown  by  dotted  lines. 


FIG.  198.  —  Square  Setting  Block. 

It  will  be  seen  that  with  this  construction  the  blade  may  be 
quickly  and  accurately  set,  and  firmly,  and  that  when  the  fine 
edge  of  the  blade  becomes  worn,  it  is  a  very  small  job  to  remove 
and  reset  it,  that  is,  if  we  have  a  block  which  is  square  to  set  to. 
Such  a  block  is  prepared  in  the  following  manner: 

It  should  be  of  steel,  either  tool  steel  hardened  through,  or 
machinery  steel,  case-hardened,  and  of  a  form  shown  in  Fig. 
198,  the  sides  or  edges  being  slightly  longer  than  the  square  blade. 

From  one  side  the  center  is  milled  out,  merely  to  make  it 
lighter  and  more  convenient  to  handle.  After  hardening  it  should 


i8o  GAGES  AND  GAGING   SYSTEMS 

be  immediately  drawn  slightly  to  take  out  the  strains,  preferably 
in  hot  sand  or  oil,  and  as  slowly  as  possible. 

It  is  then  ground  on  a  grinding  machine  on  its  flat  side  and 
four  edges,  and  all  these  are  made  as  near  square  to  each  other  as 
it  is  possible  to  get  them  by  grinding.  Then,  unless  the  job  is 
urgent,  the  block  should  be  laid  away,  the  longer  the  better,  but 
at  least  a  week,  to  allow  it  to  settle  before  beginning  to  finish  by 
lapping. 

It  will  of  course  be  understood  that  for  work  of  this  character 
the  lap  must  be  very  true  and  flat  to  be  of  any  use  whatever. 
A  good  lap  for  this  purpose,  and  for  general  tool  and  gage  work, 
is  prepared  as  follows:  It  should  be  about  15  x  24  inches,  of  cast- 
iron,  with  the  cast  face  downwards.  In  form  it  is  a  flat  plate 
2  inches  thick,  ribbed  on  the  under  side  with  ribs  f  inches  thick 
and  4  inches  deep,  arranged  like  the  ribs  on  the  Brown  &  Sharpe 
surface  plates,  and  bearing  its  weight  on  three  points  to  avoid 
springing. 

In  order  to  get  a  flat  plate  and  do  anything  like  fine  work, 
it  is  necessary  to  have  three  of  these  plates,  all  alike.  They 
should  be  planed  smooth  all  around  the  four  edges  and  on  top, 
which  should  also  have  grooves  planed  in  it  running  lengthwise 
only,  about  J  to  W  inch  apart,  and  of  a  shape  that  would  be  made 
by  a  6o-degree  thread  tool  with  the  point  slightly  rounded. 

These  grooves  should  be  about  ^\  inch  wide  at  the  top,  and 
planed  in  at  one  cut,  so  that  they  may  be  slightly  rough  on  the 
edges,  and  so  hold  the  emery  better. 

After  planing,  put  one  of  them  face  up  on  a  bench  or  box, 
where  it  can  be  got  at  from  two  opposite  sides;  turn  another 
plate  on  this  one,  faces  together,  and  with  benzine  and  No.  100 
emery  between,  and  with  two  good  strong  laborers  to  operate, 
proceed  to  grind  or  lap  them  together,  keeping  the  surface  wet 
with  benzine.  When  they  begin  to  bear  all  over,  lay  one  aside 
and  take  a  new  fresh  plate;  next  lay  aside  the  first  plate  and  lap 
together  the  second  and  third,  and  proceed  in  this  manner  until 
all  are  finished.  This  of  course  is  on  the  old  principle  that  no 
three  surfaces  can  all  fit  each  other  unless  all  are  true  planes. 

It  is  not  at  all  necessary  to  use  red  ink  or  blue  as  a  marking 
to  indicate  when  they  surface  each  other,  as  by  wiping  them  clean 
with  benzine  and  waste,  and  standing  at  some  ten  or  fifteen  feet 
—  with  the  plate  in  a  horizontal  position  between  the  eye  and 


GAGES  AND  GAGING   SYSTEMS  181 

the  window,  it  will  be  very  easy  to  see  where  the  bearing  is,  as 
of  course  there  will  be  no  small  spots  such  as  there  are  when  two 
plates  are  scraped  together.  The  high  places  will  appear  to  be 
highly  polished,  while  parts  which  do  not  bear  will  appear  dead 
and  like  ground  glass.  The  finishing  is  done  with  the  finest 
flour  emery,  and  very  little  of  that. 

When  new  they  will  warp  and  spring  out  of  shape,  and  use 
will  wear  holes  in  them,  when  they  are  once  more  put  through 
the  lapping  process  with  each  other. 

For  spreading  the  emery  and  benzine  and  charging  the  plates 
when  in  use,  it  is  well  to  have  a  cast-iron  charging  block  which 
is  about  5x7  inches  and  four  inches  thick.  On  the  top  and 
one  end  are  U-shaped  handles.  The  face,  which  is  planed,  has 
semicircular  grooves  about  \  inch  wide  and  about  I  inch  apart, 
planed  both  ways  to  form  squares.  These  grooves  form  air 
passages,  and  prevent  sting  and  hard  work.  To  charge,  apply 
emery  to  the  lap  by  shaking  it  in  from  a  box  with  small  holes 
punched  in  the  cover  like  a  pepper-pot,  wet  down  with  benzine 
from  a  common  oil  can;  then  rub  the  charging  block  over  the 
surface  from  side  to  side,  and  gradually  working  from  end  to  end 
to  cover  the  whole  surface.  This  block  is  frequently  used  also 
to  clean  and  sharpen  the  surface  of  the  lap,  when  it  is  rubbed 
over  simply  with  benzine.  For  finishing  such  work  as  we  now 
have  in  hand,  the  charging  block  is  rubbed  over  the  lap  with 
benzine  only,  and  the  lap  is  then  wiped  dry  with  the  waste,  wiping 
from  end  to  end  only,  and  with  the  grooves,  as  in  this  way  much 
less  lint  will  be  caught  than  if  we  try  to  wipe  across  them,  or  if 
the  grooves  are  planed  both  ways. 

It  is  often  convenient  in  doing  small  work  on  a  lap  of  this 
size  to  have  a  little  emery  on  one  end  and  the  other  clean,  so 
that  both  roughing  and  finishing  may  be  done  without  waste  of 
time. 

Care  should  of  course  be  exercised  to  distribute  the  wear  as 
evenly  as  possible.  On  the  start,  in  lapping  the  parts  of  the 
square,  benzine  and  flour  of  emery  or  carborundum  are  used  until 
the  wheel  marks  are  out  of  the  surfaces,  while  the  finishing  is  done 
with  the  lap  wiped  perfectly  dry  and  clean,  the  emery  bedded 
into  the  cast-iron  lap  being  sufficient  to  cut  and  polish. 

We  will  now  assume  that  the  square,  Fig.  197,  has  been  fin- 
ished, and  the  blade  and  stock  set  as  nearly  square  as  by  other 


182 


GAGES  AND  GAGING   SYSTEMS 


means.  Referring  to  Fig.  199,  which  we  will  assume  is  the  block, 
we  lap  the  side  a  perfectly  flat  and  use  it  as  a  starter.  By  lapping 
we  now  fit  the  angle  b  to  the  square.  The  testing  is  done  by 
carefully  wiping  the  square  and  block  surface  with  the  bare  hand, 
or  a  piece  of  chamois,  applying  the  square  and  holding  up  to  the 
eye  before  a  strong  light.  When  they  fit  together  so  closely  as 
to  shut  out  the  light  the  whole  length  of  the  blade,  we  proceed 
in  like  manner  to  angle  c  to  d. 

Now  when  we  get  clear  around  and  come  to  apply  the  square 
with  angle  e,  we  may  find,  as  in  the  sketch  (which  is  greatly 
exaggerated  for  illustration),  that  there  is  a  considerable  space  / 
between  the  outer  end  of  the  blade  and  the  block,  and  this  shows 
that  the  square  is  just  one  fourth  of  this  opening  over  90  degrees, 


FIG.  199.  —  Lapped  Block. 

or,  in  other  words,  that  the  "square's"  error  is  multiplied  by 
four,  as  shown  by  this  opening  on  the  last  or  final  trial.  Should 
the  opening  appear  at  the  other  end  of  the  blade,  it  would  merely 
mean  that  the  angle  is  less  than  90  degrees.  In  either  case  we 
reset  the  blade  by  one  fourth  of  the  opening  shown  as  near  as 
we  can  estimate,  and  proceed  to  fit  the  angle  to  the  square  as 
before,  and  repeat  this  process  as  many  times  as  it  may  be  neces- 
sary to  shut  out  the  light  on  all  four  corners  or  angles. 

By  having  the  surface  clean  and  dry,  and  carefully  applying 
the  edge  of  the  stock  with  the  blade  a  little  way  off,  and  working 
it  gently  to  get  the  air  out,  we  get  a  good,  firm  contact,  and 
thus  by  very  gently  working  it  down  till  the  blade  barely  touches, 
we  can  do  a  very  accurate  job ;  for  it  seems  to  be  very  well  known 
that  under  conditions  light  may  be  seen  through  an  opening, 


GAGES  AND  GAGING   SYSTEMS  183 

which  is  only  one  forty-thousandth  part  of  an  inch  wide.  This 
will  probably  be  as  close  to  square  as  we  care  to  go.  But  there 
is  another  method  of  testing  that  seems  to  admit  of  still  greater 
refinement,  and  it  is  as  follows:  After  wiping  the  block  as  clean 
as  possible  with  the  bare  hand,  there  will  still  remain  on  the  sur- 
face a  thin  film  of  moisture.  By  gently  moving  to  exclude  the 
air,  as  before,  get  the  block  and  stock  in  close  contact,  and  now 
bring  the  blade  to  bear,  and  when  it  does,  move  it  sideways,  back 
and  forth  by  the  stock  about  ^  inch,  when  upon  removal  and  in 
a  good  light  it  will  be  seen  to  have  left  a  slight  but  distinct  mark 
in  the  moisture  upon  the  surface  of  the  block.  Unless  the  mark 
extends  the  full  length  of  the  blade,  it  shows  that  while  it  may 
have  been  close  enough  to  close  out  the  light,  it  did  not  actually 
touch  all  over,  and  by  careful  work  it  may  be  made  to  do  so. 
The  color  of  this  mark  should  also  be  noted  as  it  varies  with  the 
pressure  between  the  edge  and  the  flat  surface,  and  is  another 
guide  to  refinement.  It  should  be  uniform  in  appearance  from 
end  to  end. 

The  outside  or  back  of  the  square  is  left  until  the  block  is 
completed,  when  it  is  tested  by  standing  both  block  and  square 
on  a  true  flat  surface,  and  proceeding  as  before,  except  that 
the  edge  is  now  lapped  with  a  small  hand  lap  to  bring  it  true 
instead  of  by  moving  the  screws  as  before;  and  of  course  the 
block  is  not  lapped,  because  it  has  been  previously  made  square. 

It  is  necessary  while  finishing  both  edges  of  the  blade,  to 
tilt  or  roll  it  on  an  angle  both  ways  over  its  slightly  rounded 
edge,  making  it  bear  as  shown  by  the  dotted  lines  c,  Fig.  196. 
Were  this  not  done,  the  square  might  be  anything  but  true,  if 
it  were  turned  ever  so  slightly  at  an  angle  to  the  work.  It  is 
this  rolling  over  and  making  the  edge  touch  its  full  length  in 
any  position  that  takes  the  most  time  and  patience. 

A  tool  of  this  kind  is  best  made  at  times  and  worked  in  be- 
tween other  jobs,  as  it  will  not  do  to  hurry  it  in  the  least,  and 
neither  the  block  nor  the  square  can  be  held  in  the  hand  any 
length  of  time  without  being  warped  or  expanded  out  of  shape 
by  the  heat  of  the  hand.  If  these  operations  be  extended  over 
several  months  or  years,  at  the  end  of  that  time  the  steel  will 
become  so  settled  as  to  stay  in  shape  fairly  well.  For  some  time 
after  the  block  is  started  it  will  be  noticed  that  the  corners  fall 
away  and  the  flat  surfaces  persistently  get  high  in  the  center. 


1 84 


GAGES   AND   GAGING   SYSTEMS 


A  quicker  but  somewhat  less  accurate  way  of  testing  a  square 
is  shown  at  Fig.  200.  The  piece  a  being  made  parallel  on  its 
two  sides,  the  angle  b  is  fitted  by  scraping  or  lapping  to  the  square. 
If  the  square  be  now  applied  to  angle  c,  the  error,  if  any,  will  be 
multiplied  by  2  instead  cf  by  4,  as  in  the  other  method.  This 
last  method  has  the  further  disadvantage  of  depending  entirely 
on  the  parallelism  of  the  two  sides  of  the  test-block. 

One  rule  in  squaring  work  should  be:  Hold  the  stock  against 
the  shortest  side  of  the  work,  if  there  be  one,  whether  that  side 
is  to  be  changed  or  corrected  or  not.  In  this  way  the  angle  or 
error,  if  there  be  one,  between  the  work  and  the  blade  is  extended 


FIG.  200.  —  Testing  a  Square. 

and  much  more  readily  seen  than  if  applied  to  a  short  surface, 
such  as  the  end  of  the  bar. 

It  will  perhaps  seem  to  some  good  workmen  that  the  square 
and  block  above  described  are  carried  to  an  unnecessary  degree 
of  refinement  for  the  result  that  is  to  be  attained. 

To  illustrate  its  use,  we  will  consider  the  making  of  a  snap 
gage  of  the  style,  Fig.  201,  composed  of  a  core  a,  having  its  jaws 
b  secured  by  screws  to  its  two  edges.  It  will  of  course  be  under- 
stood that  the  two  edges  of  the  core  a  must  be  parallel  to  each 
other,  and  with  the  aid  of  such  a  square  as  described,  it  may 
be  very  quickly  tested  by  squaring  from  one  flat  side  which  is 
previously  finished  for  convenience  in  grinding.  Again,  for 


GAGES  AND  GAGING  SYSTEMS 


"85 


making  the  test  piece  or  end  measure,  Fig.  202,  which  is  some- 
times used  in  connection  with  Fig.  201,  the  two  end  surfaces 
must  be  parallel  to  each  other,  and  that  is  most  quickly  tested 
by  having  two  sides,  as  a  b,  finished,  though  not  necessarily  square 
to  each  other,  and  squaring  from  these  sides  both  ways  over 
each  end.  These  illustrations  will  serve  to  indicate  many  uses 


FIG.  201.  —  Snap  Gage. 

to  which  such  a  tool  may  be  put,  and  where  the  time  required 
for  testing  would  be  only  a  small  fraction  of  what  would  be 
required  for  a  test  by  measurement. 

A  PRECISION  SQUARE 

The  ordinary  try-square  indicates  plainly  enough  when  a 
piece  of  work  to  which  it  is  applied  is  out  of  square,  provided 
a  good  light  is  obtainable;  but  when  the  variation  is  very  slight 


FIG.  202.  —  End  Test  Piece. 

the  light  must  be  a  strong  one,  and  the  amount  of  variation 
must  always  be  estimated;  it  is  not  directly  indicated. 

We  present  herewith  drawings  of  a  square  which  is  much 
less  dependent  upon  strong  light — i.e.,  a  square  which  does 
not  require  that  light  shall  shine  directly  through  between  the 
blade  and  the  work;  and  one  which,  while  it  still  leaves  the  varia- 
tion from  the  true  right  angle  to  be  estimated,  very  materially 
assists  in  estimating  correctly. 


1 86 


GAGES  AND   GAGING   SYSTEMS 


:The  square  is  the  invention  of  G.  A.  Bates.  The  blade  is 
pivoted  at  A,  Fig.  203,  and  can  move  through  a  small  arc.  In 
doing  so  it  moves  an  indicating  lever  B,  which  is  pivoted  at  C, 
and  connected  to  the  blade  at  D;  the  result  being  that  when  the 
blade  is  moved  in  one  direction  the  lever  moves  in  the  opposite 
direction  through  a  much  greater  arc,  and  the  variation  between 
the  two  lines  shown — one  drawn  upon  the  upper  end  of  the 
lever,  and  the  other  on  an  adjustable  plate  attached  to  the  blade 
—  is  many  times  the  variation  of  the  work  from  a  true  right 


FIG.  203.  —  Precision  Square. 

angle,  and  the  slightest  variation  is  very  readily  seen  even  when 
it  is  difficult,  or  even  impossible,  to  see  between  the  blade  and 
the  work,  as  is  required  to  be  done  with  the  ordinary  square. 
At  the  same  time,  when  it  is  desirable  to  clamp  the  blade  either 
square  with  the  stock  or  at  a  slight  angle  to  it,  as  is  sometimes 
required,  it  is  readily  done  by  simply  turning  the  knurled  screw 
E  at  the  end  of  the  stock,  the  action  upon  this  screw  of  the  clamp- 
ing lever  F  being  clearly  indicated.  It  is  needless  perhaps  to 
remark  that  the  clamp  has  not  the  slightest  tendency  to  disturb 
the  adjustment  of  the  blade. 


GAGES  AND  GAGING   SYSTEMS 


187 


To  insure  that  there  shall  be  no  lost  motion  in  the  connectidh 
between  blade  and  indicating  lever,  the  pin  which  connects  them 
is  fixed  in  the  blade,  and  the  hole  in  the  lever  is  opened,  as  is 
shown,  and  the  spring  piece  a  is  slightly  depressed  so  that  it 
always  bears  snugly  against  the  pin.  NThe  corner  between  the 
blade  and  stock  is  opened  slightly,  as  shown,  so  that  trouble 
from  dirt  collection  there  is  avoided.  Fig.  204  shows  the  stock 
separately. 

In  using  a  sample  square,  from  which  our  engravings  were 
prepared,  Mr.  Bates  found  it  to  be  capable  of  standing  tests  of 
very  great  refinement,  and  at  Fig.  205  we  show  a  device  gotten 
up  for  testing  and  adjusting  the  square.  It  is  called  an  adjusting 
testing  block,  and  is  composed  of  an  approximately  square  block 
having  a  groove  planed  around  its  four  sides,  as  shown  in  the 


FIG.  204.  —  Stock  of  Precision  Square. 

partial  section  at  the  right.  Into  this  groove  are  fitted  four 
pieces  which  are  pivoted  at  one  end,  and  at  the  other  end  can 
be  adjusted  by  the  screws  shown;  the  larger  screw  raising  the 
pieces,  and  the  other  smaller  screws  having  the  opposite  tendency, 
so  that  by  their  combined  action  the  piece  is  readily  adjusted 
and  firmly  held. 

Starting  as  accurately  as  possible,  two  of  these  pieces,  ad- 
jacent to  each  other,  were  adjusted  to  fit  the  square,  and  the 
block  was  then  adjusted  around  to  the  place  of  beginning  where 
the  error  of  the  square  was  shown  magnified  in  a  way  familiar 
to  all  mechanics  who  have  ever  tried  to  make  a  block  really 
square  on  four  sides.  This  error  was  then  divided  and  adjusted 
as  nearly  as  possible,  and  the  process  repeated  until  the  square 
would  go  all  around,  showing  the  least  variation.  It  was  then 
assumed  that  both  testing  blocks  and  square  were  really  square, 
as  in  fact  they  were. 


1 88 


GAGES   AND  GAGING   SYSTEMS 


This  has  been  patented  by  its  inventor,  who,  as  a  result  of 
his  experience  with  it,  calls  it  his  "precision"  square.  A  speci- 
men we  have  had  the  privilege  of  examining  is  certainly  an  ad- 
mirable tool,  whether  considered  as  a  piece  of  fine  tool  making, 
or  in  respect  to  its  action  when  in  use. 

A  REMARKABLE  SURFACE  GAGE 

This  surface  gage  is  the  original  of  its  kind.  It  was  designed 
by  George  Win  cock,  a  man  celebrated  in  the  old  gun,  and  early 
sewing-machine  days.  It  was  made  in  the  Mott  Street  factory 
of  the  Singer  Company,  about  the  year  1867,  perhaps  before. 


FIG.  205.  —  Device  for  Adjusting  Square. 

In  1868  rumors  of  a  remarkable  tool  of  this  kind  became  the 
subject  of  shop  talk  among  tool-makers  in  New  York  City,  in 
Hartford,  in  Boston,  and  elsewhere,  in  consequence  of  the  migra- 
tions and  professional  tours  of  members  of  that  aristocratic  guild 
of  mechanics  who  had  seen  and  described  it. 

Tool-makers  in  those  days  were  favored  creatures,  and  Win- 
cock  was  a  king  among  them.  He  went  into  the  shop  in  the 
morning  dressed  in  faultless  fashion,  with  gloves  and  silk  hat. 
Imagine  a  man  standing  at  the  vise  in  lavender  trousers  and  a 
duck  vest,  with  his  shirt  sleeves  rolled  back,  and  a  silk  handker- 
chief for  an  "apron."  The  handkerchief  corners  would  be  tucked 
into  his  vest  pockets  for  a  fastening.  Then  believe  the  still 


GAGES  AND  GAGING   SYSTEMS  189 

more  marvelous  fact  that  neither  of  the  garments  would  be  soiled, 
and  the  "apron"  would  last  a  week  quite  clean,  and  a  man  thus 
clothed  would  do  as  much  first-class  work  as  any  other  man  then 
or  since.  Wincock  was  a  whole  man  in  the  shop  and  out  of  it, 
and  many  of  the  old-timers  remember  his  kindness  of  heart  as 
well  as  his  other  peculiarities. 

Later  on  the  gage  did  good  service  in  the  United  States  Watch 
Factory,  Marion,  N.  J.,  where  Wincock  arrived  in  1874,  and 
began  a  mercantile  career.  Having  no  further  use  for  this  tool, 
he  gave  it  to  a  friend  —  first  to  show  to  some  of  his  friends  - 
and  when  he  carried  it  back  to  him  he  said,  "Keep  it;  you  are 
the  only  man  out  here  that  I  knew  at  the  bench,  and  you  have 
use  for  it,  I  haven't."  He  said  that  it  cost  him  about  one  hun- 
dred and  fifty  dollars  to  make  it.  The  friend  still  possesses  it, 
and  it  has  continually  reflected  credit  on  its  designer.  Every 
mechanic  accepts  its  decisions  when  it  is  carefully  applied  to 
use.  Its  service  to  the  owner  personally  is  and  has  been  incal- 
culable. He  has  been  able  to  prove  perfections  and  detect  errors 
with  his  instrument,  which,  without  it,  would  in  certain  cases 
either  have  cost  its  value  to  provide  as  accurate  special  appliances 
for,  or  the  results  obtained  would  have  been  in  doubt. 

While  the  readings  on  the  scale  have  no  positive  value,  a 
person  experienced  in  using  this  gage  can  detect  differences  of 
less  than  .0003  inch  between  one  hight  and  the  other  when  they 
are  compared.  Fig.  206  is  the  front  elevation  of  this  gage.  Fig. 
207  is  a  horizontal  section  cut  through  the  base,  showing  the 
construction  of  the  peculiar  ornamentation  of  that  part,  and 
the  shape  of  the  seat  below  it.  Fig.  208  is  a  horizontal  section 
through  the  head,  and  Fig.  209  is  the  view  of  the  bracket  H, 
showing  its  construction  and  the  arrangement  of  the  worm  K 
upon  it,  as  well  as  the  hub  /  by  which  the  whole  head  is  attached 
to  the  support  G. 

We  have  never  seen  one  of  these  gages  made,  and  do  not  know 
how  all  the  operations  on  it  are  performed,  but  we  do  know  that 
they  can  be  made.  The  base  C  seems  to  be  bored,  as  indicated 
by  the  dotted  lines,  and  the  column  G,  with  the  sub-base  D  in 
one  piece,  is  let  through  the  base  C,  and  fits  it  tightly.  If  this 
column,  after  it  has  been  roughly  turned,  is  carefully  trued  in 
a  chuck  on  a  dividing  head,  with  the  lower  head  outward,  and 
placed  before  a  drilling  head  at  the  proper  angle  and  one  hole 


190 


GAGES   AND   GAGING   SYSTEMS 


FIGS.  206  to  209.  —  Remarkable  Surface  Gage. 


GAGES  AND  GAGING   SYSTEMS  191 

carefully  drilled  to  the  size  of  the  small  end  of  the  taper  plugs  E, 
which  make  the  convex  fluting  in  the  sub-base,  then  if  the  dividing 
head  should  be  turned  one-sixth  the  circle  and  another  hole  drilled, 
and  thus  for  the  remaining  four  holes  each  to  the  proper  depth, 
all  would  be  located  in  their  proper  position.  It  is  understood 
of  course  that  there  is  solid  stock  all  about  these  holes  when  they 
are  drilled,  and  that  the  holes  extend  by  a  short  distance  above 
the  tops  of  the  flute  visible  in  Fig.  206.  The  plugs  E  seem  to 
have  the  taper  of  the  ordinary  pentagon  pin  broach,  so  we  pre- 
sume they  were  reamed  by  hand.  After  reaming,  they  should 
be  fitted  with  temporary  plugs,  which  should  be  well  greased 
and  driven  in  snugly.  The  plugs  should  be  of  brass,  so  that  the 
color  may  guide  the  operation,  because  it  is  probable  that 
the  joints  will  not  otherwise  be  seen  in  turning  and  polishing 
the  sub-base.  After  the  column  is  completely  finished  in  every 
other  particular,  these  temporary  plugs  are  removed  and  others 
of  polished  steel  are  driven  into  their  places,  giving  the  effect 
shown. 

The  cap  F  is  an  independent  piece,  and  at  its  knurled  flange 
is  larger  than  the  column  G,  to  prevent  the  accidental  removal 
of  the  head.  The  top  of  the  column  is  drilled  and  tapped,  and 
the  cap  F  is  provided  with  a  screw  stem  which  fits  it,  the  joint 
being  directly  under  the  knurled  flange. 

The  base  C  on  this  column  is  soft  steel,  and  as  such  inferior 
because  it  catches  grit  and  scratches  on  a  surface  plate;  hence 
this  base  and  column  have  not  been  used  by  the  writer.  In  its 
place  a  hardened  steel  base  of  circular  outline  was  made,  to  which 
was  fitted  a  column  double  the  hight  of  this  one.  This  overcame 
the  trouble. 

The  bracket  H,  shown  in  Figs.  208  and  209,  has  within  the 
hub  /,  which  fits  the  column  G,  a  spring  gib  or  shoe  I1,  which 
covers  the  point  of  the  screw  H1,  and  prevents  it  from  marring 
this  column.  The  probable  construction  of  the  gib  is  indicated 
by  these  sections.  We  can  find  no  joint,  but  believe  the  sleeve 
/  to  be  inserted  within  the  bracket  H  after  the  gib  has  been 
made,  as  shown.  The  worm  extension  H2  seems  to  be  a  solid 
part  of  the  bracket  H,  which  it  may  very  well  be.  It  is  presumed 
that  the  worm  is  keyed  on,  as  shown  in  Fig.  209. 

The  worm  gear  /  loosely  fits  the  bracket  H2,  and  engages  the 
worm  K.  It  is  recessed  to  receive  the  circular  plate  M  of  the 


192  GAGES  AND  GAGING   SYSTEMS 

adjustable  stock  M  R  R.  This  plate  is  penetrated  by  the  hub 
of  the  bracket  H;  it  is  covered  by  the  washer  N,  and  clamped 
by  the  screw  O.  The  dowels  P  enter  the  slot  Pl  of  the  washer  N, 
and  prevents  it  turning.  The  worm  K  is  used  only  in  fine  adjust- 
ment. When  the  screw  0  is  loose,  the  adjustable  stock  M  R  R 
may  freely  be  turned  in  any  position,  because  the  plate  M  has  a 
circular  seat.  When  the  screw  O  is  partly  tightened,  the  worm 
can  adjust,  but  when  wholly  tight  it  holds  the  stock  rigidly  in 
its  position. 

The  stock  M  R  R  supports  the  gage  arm  T,  and  secures  it 
to  the  required  position  by  means  of  the  screws  5  S.  The  beak 
of  the  arm  T  is  bored  vertically,  of  a  parallel  small  size,  to  which 
is  fitted  very  carefully  the  plunger  W,  so  as  not  to  shake  but  to 
be  quite  free,  so  as  to  slide  end-wise  with  perfect  ease.  This 
plunger  is  kept  in  place  by  a  shoulder  which  rests  on  the  arm 
T,  and  it  has  a  small  hemispherical  tip  which  receives  the  short 
arm  of  the  index  X.  This  index  X  is  pivoted  in  the  fulcrum 
post  Y  one-tenth  of  an  inch  from  the  center  of  the  plunger  W. 
It  must  have  perfect  freedom  on  its  fulcrum,  and  be  well  guided 
in  its  position.  The  spring  /  is  attached  to  the  post  I1,  and  has 
stiffness  just  sufficient  to  surely  overbalance  the  weight  of  the 
index  arm  and  keep  a  pressure  upon  the  plunger  W.  The  value 
of  this  gage  as  a  delicate  instrument  depends  on  the  adjustment 
of  these  parts,  but  when  they  are  correctly  set  they  will  remain 
so  for  years.  Since  we  have  had  this  gage  it  has  required  two 
new  plungers  and  one  new  spring. 

The  scale  V  has  been  lost  many  years.  It  is  of  but  little 
value  because  it  is  found  better  to  gage  from  a  touch,  or  when 
the  plunger  W  just  touches  the  work  so  that  the  index  at  its 
outer  end  is  perceptibly  disturbed. 

The  scratch  point  U  is  hardened  and  screws  into  the  arm  T, 
precisely  as  cap  F  does  into  G.  It  has  never  been  used. 

The  uses  of  these  special  features  should  be  clear  to  every 
mechanic,  where  they  apply  to  the  detection  or  the  confirming 
of  hights  and  parallels,  and  it  is  only  necessary  to  say  that  it 
is  better  practice  to  set  the  gage  to  the  lower  piece,  or  end,  and 
at  the  higher  place  to  place  paper  of  uniform  thickness  under 
the  base  of  the  gage  until  the  difference  is  equaled.  Then  measure 
the  paper  with  micrometer  gage.  Handle  the  gage  with  a  cloth 
tied  to  it  whenever  the  hand  comes  in  contact,  because  a  warm 


GAGES  AND  GAGING   SYSTEMS  193 

hand  will  expand  a  length  of  four  inches  about  three  thousandths 
of  an  inch  at  times.  This  has  explained  many  contradictions 
in  our  experience. 

In  turning  or  grinding  cylinders  this  gage  will  give  the  truth 
of  the  result,  and  frequently  surprise  the  opera-tor  who  imagines 
he  is  getting  a  perfectly  concentric  job.  To  do  this,  stand  the 
gage  on  a  flat,  rigid  surface,  and  set  the  front  of  the  plunger  W 
on  the  top  of  the  revolving  surface.  The  index  will  show  whether 
it  is  true,  eccentric,  or  not  round.  If  true  the  index  will  stand 
dead  still;  if  eccentric  it  will  rise  and  fall  regularly;  if  not  round 
it  will  rise  and  fall  irregularly. 

Work  in  the  lathe  being  trued  up  can  be  proved  in  the  same 
manner  by  this  gage.  Lathe  centers,  milling  arbors,  and  in 
fact  all  arbors,  can  be  inspected  by  the  same  method.  Face- 
plates and  shoulders  can  be  tried  for  truth  as  well  as  cylinders, 
by  turning  the  gage  arm  one-quarter  way  over  to  meet  them 
squarely.  In  fact,  every  rotation  piece  may  be  inspected  per- 
fectly for  truth  by  this  tool. 

In  the  sketch  here  given,  it  is  believed  that  the  device 
is  fairly  well  shown.  Considering  the  fact  that  it  was  designed 
and  made  so  many  years  ago,  it  is  wonderful  that  it  exhibits  so 
much  that  has  been  proved  to  be  correct  practice,  and  if  it  were 
a  production  of  to-day  it  would  be  considered  as  being  ahead  of 
progress  rather  than  behind  it. 

A  MICROMETER  HIGHT-GAGE 

The  sketch,  Fig.  210,  is  of  a  hight  gage  made  on  a  plan  of  a 
surface  gage.  It  consists  of  a  central  standard  fixed  in  a  base. 
The  standard  is  threaded  throughout  its  length  1 6  threads  (or 
any  number,  for  that  matter),  and  then  the  threads  are  milled 
away,  leaving  a  section  on  two  opposite  sides  threaded,  and  on 
two  opposite  sides  blank.  The  inside  of  the  nut  enclosing  the 
standard  is  relieved  on  two  sides  to  correspond.  This  enables 
the  rapid  moving  up  or  down  of  the  arm  by  simply  loosening  the 
clamp  screw  that  binds  it,  turning  it  one  fourth  of  the  way  around 
and  then  sliding  it  to  the  desired  hight,  swinging  it  round  to  a 
square  position,  and  fastening  the  screw  again.  To  locate  the 
arm  just  right,  a  needle  point  is  fixed  on  the  top  of  the  arm,  that, 
with  the  marks  on  the  standard,  determines  its  location  and  sets 


194 


GAGES  AND  GAGING   SYSTEMS 


it  central.  The  arm  is  extended  and  holds  a  round  button  of 
steel  with  hardened  face.  This  button  is  bored  and  threaded  to 
fit  on  a  screw  fastened  in  the  end  of  the  arm,  as  shown.  Said 
screw  is  in  a  recess  which  is  filled  by  the  button.  This  button 
has  50  graduation  marks  on  its  circumference,  and  the  screw 


/Hardened  Face 


50  Graduations 


Thread  20  to  the  Inch 


FIG.  210.  —  Micrometer  Hight  Gage. 

is  threaded  20  to  the  inch,  allowing  adjustments  of  one  thousandth 
of  an  inch. 

The    standard,   graduated   to   sixteenths,    makes   a   familiar 
reading,  and  the  finer  measurements  can  be  obtained  from  the 


GAGES  AND  GAGING   SYSTEMS  195 

micrometer  button.  The  top  face  of  the  button  when  set  at 
zero  is  equal  to  the  hight  of  nut  on  the  standard  at  the  reading 
point.  The  button  is  limited  to  two  revolutions,  as  the  arm 
can  be  shifted  to  make  the  difference,  and  a  reading  of  less  than 
zero  on  the  button  is  possible,  thus  compensating  for  the  difference, 
between  the  sixteenth  threads  on  the  standard  and  the  twenty 
threads  on  the  button. 

The  clamp  screw  is  to  have  a  soft  metal  seat  to  bear  against 
the  thread  when  fastening  the  arm  in  place;  the  whole  to  be 
finished,  making  a  handy,  quick  and  reliable  tool. 


SECTION   VIII 

OUTSIDE  MICROMETER  CALIPERS,  TOGETHER  WITH 
THEIR  ATTACHMENTS  FOR  SPECIAL  MEASURING 
AND  GAGING. 

MICROMETER  FOR  SCREW  THREADS 

THE  first  micrometer  of  the  thread-measuring  type  with  which 
we  are  all  familiar  was  apparently  made  so  nearly  right  that  it 
has  not  seemed  worth  while  to  change  it  after  mechanics  have 
become  so  accustomed  to  its  use.  We  suppose  that  if  the  screws 
had  been  cut  originally  25  to  50  to  the  inch  instead  of  to  40,  the 
other  divisions  being  made  to  correspond,  the  tool  would  have 
been  just  as  satisfactory.  And  so  when  we  propose  improvements, 
it  behooves  us  to  make  haste  slowly  in  order  that  the  improve- 
ment may  become,  like  the  micrometer  itself,  a  permanent  one. 

The  device  we  have  in  mind  is  for  accurately  measuring  screws, 
and  without  reflecting  on  the  efficiency  of  the  other  devices, 
we  will  say  that  this  is  a  practical,  satisfactory  device,  and  so 
decided  in  a  large  screw-manufacturing  concern  after  experi- 
menting with  everything  known  in  this  line.  It  is  nothing  but 
a  pair  of  spherical  points  attached  to  a  standard  micrometer, 
as  shown  in  Fig.  211.  These  points  find  a  bearing  just  where 
the  nut  should  fit  the  screw.  If  we  have  a  nut  and  bolt  perfectly 
fitting  each  other,  and  proceed  to  take  a  cut  off  the  outside  of 
the  bolt,  we  cannot  observe  any  difference  in  the  fit;  so  that 
we  very  often  find  that  the  diameter  of  the  nut  inside  cuts  very 
little  figure  in  the  fit.  What  we  propose  is  to  have  sets  of  spheres 
of  standard  sizes,  with  the  standard  projections  from  the  face 
of  the  anvil.  The  spheres  should  be  so  large  as  not  to  strike  the 
bottom  on  the  standard  screw,  and  small  enough  to  go  below 
the  top  of  the  "V."  We  estimate  that  one  pair  of  spheres  will 
answer  for  five  or  more  pitches,  and  by  having  all  fitted  alike 
we  take  in  fine  threads  of  large  diameter,  and  all  odd  sizes  within 

196 


GAGES  AND  GAGING  SYSTEMS 


197 


the  limits  of  our  tools.  Then  if  there  was  not  too  much  of  an 
opening  in  the  anvils,  the  micrometers  could  be  used  for  ordinary 
work  as  well.  The  size  when  the  spheres  are  in  place  should 
be  stamped  on  each. 

The  usual  custom  in  screw  factories  is  to  have  a  set  of  hard- 
ened and  ground  gages,  and  when  making  taps  to  take  the  size 
from  the  gages  with  the  spherical  point  micrometers.  Now  if 
it  was  known  what  these  sizes  were,  it  would  not  be  necessary 
to  have  the  gages.  These  gages  are  so  expensive  as  to  debar  all 
except  the  largest  companies  from  enjoying  the  luxury.  A 
maker  of  micrometers  could  get  up  an  index  giving  all  these 


FIG.  211.  —  Micrometer  for  Screw  Threads. 


sizes  for  standard  screws,  and  all  screws  could  be  ordered  by 

these  micrometers,  thus: 

Nominal  size,  "V"  thr.  per  inch, 

i  inch  13 

Bearing  size  measured  with  No.  5  point,     .627. 
It  would  not  be  necessary  to  mention  No.  5  points,  as  each 

would  have  an  index  stating  what  pitches  each  pair  of  points 

was  adapted  to;  and,  they  being  alike,  the  man  in  San  Francisco 

would  measure  exactly  like  the  man  in  Boston. 

MEASURING  EXTERNAL  SCREW  THREADS  WITH  THE  MICROMETER 

Figs.  212  and  213  illustrate  an  improved  method  of  measuring 
screw-thread  diameters  in  the  thread  angle  by  using  ordinary 


198 


GAGES  AND  GAGING  SYSTEMS 


micrometer  calipers  and  wires  of  a  suitable  diameter.  Without 
doubt  this  is  one  of  the  most  accurate,  as  it  has  come  to  be 
one  of  the  most  universal,  methods  in  use.  Since  we  became 
acquainted  with  it  and  learned  its  usefulness,  we  have  used  it 
successfully  on  all  available  work,  but  find  it  very  inconvenient 
to  hold  the  wires,  a  screw  plug  and  the  micrometer  calipers  all 
at  once.  Therefore  we  have  made  a  slight  improvement  in  the 
tool,  placing  it  upon  a  stand  with  three  legs.  A  hardened  and 


S       e 


FIGS.  212  and  213.  —  Screw  Measuring  Micrometers. 

lapped  disk  is  screwed  on  the  top  of  the  stand,  as  shown,  as  it 
gives  a  better  measuring  surface  and  is  easier  to  handle. 

In  shops  where  the  work  is  of  great  accuracy  and  only  the 
practical  minimum  limit  of  error  or  variation  is  allowable,  two 
sets  of  test  micrometers  should  be  provided,  one  for  general  use 
and  the  other  for  occasional  reference  only.  The  new  microm- 
eters should  be  given  to  the  most  skilled  workmen  for  use  on  the 
finest  work  only,  while  those  micrometers  which  have  become 
worn,  or  are  to  a  certain  extent  inaccurate,  should  be  used  on 
work  in  which  a  greater  limit  of  error  is  allowed. 


GAGES   AND   GAGING   SYSTEMS 


AN  EQUATING  MICROMETER 


199 


A  very  ingenious  micrometer  and  recording  gage  of  English 
design  is  illustrated  in  Fig.  214.  The  micrometer  portion  of  this 
instrument  follows  the  usual  lines  of  construction,  except  that 
the  barrel,  which  is  usually  knurled,  is  in  this  case  formed  into  a 
multiple-threaded  worm  which  operates  a  disk  mounted  below 
and  carrying  a  series  of  figures  representing  various  equivalents 
of  the  measurement  made  by  the  jaws  of  the  micrometer.  A 
bracket  is  fastened  to  the  bow  of  the  micrometer  for  carrying 
this  worm  disk,  and  there  is  also  a  fixed  disk  which  stands  in 
front  of  the  revolving  one  and  has  a  series  of  holes  through  which 


FIG.  214.  —  Equating  Micrometer. 

the  numbers  on  the  revolving  disk  become  visible  as  the  work 
is  rotated. 

As  shown  in  the  cut,  the  jaws  of  the  micrometer  are  set  at  .3 
inch,  and  on  the  dial  may  be  read  its  metric  equivalent  7.62 
millimeter;  also  300,  denoting  the  number  of  thousandths;  and 
i,  over  S.  W.  G.  indicating  that  .3  is  the  equivalent  of  No.  i 
Stubbs  wire  gage.  At  the  bottom  of  the  disk  is  another  dial  for 
Stubbs  steel  wire,  in  which  the  size  N  is  indicated.  This,  how- 
ever, is  slightly  misleading  as  the  letter  will  not  occupy  the  exact 
center  of  the  opening  until  the  jaws  of  the  micrometer  have 
been  moved  .002  inch  more,  giving  an  opening  of  .302.  A  line 
on  the  worm  disk  corresponding  with  a  similar  line  on  the  beveled 
edge  of  the  hole  in  the  outer  disk  indicates  when  the  exact  open- 
ing is  reached.  It  is,  of  course,  perfectly  practical  to  apply  this 


2OO 


GAGES  AND  GAGING  SYSTEMS 


arrangement  to  any  kind  of  measurements  for  which  the  microm- 
eter may  be  used,  and  in  place  of  the  equivalents  here  indicated 
we  may  have  fractions  of  an  inch,  sheet  metal  gages,  screw  sizes, 
or  any  other  equivalents  that  may  be  desired  by  the  user.  This 
instrument  is  manufactured  by  Grinshaw  &  Baxter,  London, 
England. 

6-lNCH  BEAM  MICROMETER 

The  sketch,  Fig.  215,  shows  a  6-inch  beam  micrometer  that 
any  mechanic  can  make  with  little  trouble.  After  the  forgings 
are  shaped  out,  holes  are  drilled  and  reamed  approximately  .1 
inch  apart,  and  taper  eccentric  pieces  to  fit  held  in  position  by 


Open  \i  "and  Set  at  let  Eccentric  Stutf 


Open 


FIG.  215. —  Beam  Micrometer. 

screws  as  shown.     The  pins  can  be  easily  adjusted 
by  turning  the  eccentric  studs. 

lox  12  INCH  MICROMETER  CALIPER 


inch  apart 


Fig.  216  is  a  sketch  of  a  pair  of  lox  12  inch  micrometers 
that  are  very  easily  made.  With  the  standard  gages  3,  5,  7,  9 
and  1 1  inches,  one  can  set  at  any  place.  This  one  was  made 
from  one  end  to  the  other  complete,  as  at  the  time  the  tool  was 
made  it  was  not  possible  to  get  micrometer  heads.  The  beam 
is  of  tool  steel  — not  annealed  —  and  all  screws  are  hardened. 


How  TO  MAKE  A  LARGE  MICROMETER 

We  have  often  thought  how  handy  it  would  be  to  have  a 
large  micrometer.     We  could  measure  our  work  and  tell  just 


GAGES  AND  GAGING  SYSTEMS 


201 


how  much  was  to  come  off,  and  as  most  feed  screws  are  graduated 
it  would  be  an  easy  matter  to  feed  in  so  many  thousandths,  and 
the  work  would  caliper  just  what  we  wanted  it  to.  We  hap- 
pened to  see  a  micrometer  head  at  $3.50.  It  struck  us  imme- 


FIG.  216.  —  Twelve-Inch  Micrometer. 


diately  that  it  was  just  the  thing  we  could  use.  After  seeing 
this  micrometer  head,  we  began  to  think  there  was  no  reason 
why  we  should  not  frame  and  attach  that  head  to  it,  then  all  it 
would  cost  us  would  be  the  price  of  the  head.  We  started  in 


r 

,  ,  —    _— 

3 

IP 

i 

j 

X 

\ 

• 

1 

\ 

i 

i 

\ 

\ 

I  0     0 

0        0 

o 

' 

p       ..£ 

1   ^     f 

o!:bj 

;  o    i 

O    y 

A 

FIG.  217.  —  Large  Micrometer. 

and  in  due  time  finished  the  micrometer,  which  we  have  since 
found  very  valuable. 

We  think  the  drawings,  Figs.  217  to  220,  will  clearly  show 
the  shape  and  relative  sizes  of  the  different  parts  required.  The 
beam  and  two  carrier  arms,  Figs.  218  and  219,  were  made  from 
drawn  stock;  the  side  piece  5  was  cut  from  sheet  steel  about  TV 


202 


GAGES  AND  GAGING  SYSTEMS 


inch  thick.  Holes  were  drilled  and  the  parts  riveted  together 
with  the  beam  between  to  keep  them  the  proper  distance  apart. 
The  riveting  ought  to  be  invisible  after  it  is  polished.  The  clamp- 
ing device  which  holds  the  micrometer  consists  of  a  holder  H, 
which  by  means  of  the  nut  N  draws  the  micrometer  down  on  the 


o   o 
S 

o    o 


D 


FiGS.  218  and  219.  —  Details  of  Large  Micrometer. 

"V"  cut  on  top  of  Fig.  219.  The  holder  was  made  from  a  piece 
J  x  f  x  j,  drilled  and  cut  in  shape,  as  shown  by  the  dotted  lines 
in  Fig.  220.  The  screw  was  afterwards  inserted  and  pinned. 
The  advantage  of  having  the  micrometer  detachable  is  plain, 
as  it  can  be  used  elsewhere  for  distance  as  a  depth  gage.  For 
accurate  measurements  distance  rods  are  necessary.  They  can 


FIG.  220.  —  Details  of  Large  Micrometer. 

be  made  in  the  following  manner:  First,  run  the  micrometer  out, 
reading  1000  against  the  anvil;  then  run  it  back  to  zero  to  fit 
in  the  i-inch  rod.  Next  move  the  micrometer  back  and  run  it 
out,  reading  1000  against  the  i-inch  rod,  and  repeat  the  first 
operation,  and  so  by  continuing  as  many  distance  pieces  may 
be  made  as  would  be  desired.  We  recommend  copying  shop 
standards,  if  any  such  are  obtainable. 


GAGES  AND   GAGING   SYSTEMS  203 

As  both  carrier  arms  are  movable,  they  may  be  put  on  any 
length  of  beam;  but  the  size  for  measuring  6  inches,  we  think, 
will  be  found  most  convenient. 

LARGE  MICROMETER  CALIPERS  AT  THE  BRITISH  WESTINGHOUSE 

WORKS 

We  are  pleased  to  place  before  our  readers  a  partial  descrip- 
tion of  another  set  of  large  aluminum  zinc  calipers,  of  which 
one  size  is  shown  in  Fig.  221,  that  may  in  a  sense  be  said  to  be 
the  descendant  of  those  illustrated  in  Section  I,  having  been 
made  and  being  in  use  in  the  Manchester  Works  of  the  BritisH 
Westinghouse  Electric  &  Manufacturing  Company,  Limited. 

No  special  novelty  of  design  is  claimed.  The  sizes  range  from 
12  to  48  inches,  each  size  up  to  36  covering  4,  and  above  that 
size  6  inches,  each.  The  part  of  the  design  that  consumed  the 
most  time  was  the  adjustable  tail  spindle  (anvil),  as  the  short- 
comings of  the  m-thread-per-inch  and  half-nut  clamp  method 
had  been  noted.  The  method  employed  is  much  more  expensive, 
but  still  not  wholly  satisfactory,  the  principal  trouble  with  it 
being  to  keep  it  in  a  state  for  its  proper  use,  which  is  part  of  the 
trouble  with  any  tool  that  is  used  by  many. 

The  tail  spindles  are  of  tool  steel  ground  to  ^g-inch  diameter, 
each  clamped  in  a  reamed  ^-inch  hole  in  tail  end  of  micrometer 
frame,  by  two  ££  screws  provided  with  knurled  nuts,  as  shown 
in  Fig.  222.  This  provision  is  ample  with  proper  use.  The 
tail  spindle  shown  in  Fig.  223  is  hollow  and  provided  with  a  Cl- 
inch rod  through  the  center.  The  anvil  is  hardened,  ground  and 
lapped.  It  was  made  £|  inch  because  that  is  the  diameter  of 
the  commercial  micrometer  screws  used  at  the  head  of  the  mi- 
crometer frame.  The  accompanying  sketches  will  plainly  show 
the  construction  of  tail  pieces  and  method  of  clamping.  With 
this  tail  spindle  ready  adjustment  to  zero  is  secured. 

While  these  micrometers  were  being  planned  and  made,  no 
method  of  taking  measurements  with  the  larger  ones  had  been 
decided  upon.  The  chain  and  spring-supported  stirrup  leave 
much  to  be  desired.  Before  the  first  measurement  was  taken 
with  a  large  one,  the  method  shown  in  Fig.  221,  with  the  anvil 
at  the  top,  had  been  decided  upon,  and  it  instantly  proved  its 
adaptability  to  the  most  delicate  measurements;  .0005  inch 


204 


GAGES  AND  GAGING   SYSTEMS 


variation  in  size  being  readily  detected,  as  it  would  be  with  a 
i -inch  or  2-inch  micrometer. 


FIG.  221.  —  Large  Micrometer. 

The  advantage  of  this  method  is  obvious.  The  hand  is  at 
the  point  of  contact;  it  is  not  also  on  the  frame,  distorting  it  with 
warmth;  but  the  greatest  advantage  lies  in  the  fact  that  the 
micrometer  hangs  in  stable  equilibrium.  The  workman  says: 


GAGES  AND  GAGING  SYSTEMS 


205 


"  It  comes  up  to  the  work  itself,"  not  wanting  to  leave  the  highest 
point  of  the  work.  The  only  care  necessary  to  secure  this  ad- 
vantage is  to  place  the  anvil  at  the  proper  hight,  which  hight 
after  the  first  few  trials  is  generally  guessed  correctly  to  within 
an  inch,  the  necessary  adjustment  taking  but  a  few  seconds. 

By  the  half-tone  the  I-beam  section  and  general  outline  of 
the  frame  will  be  seen.  While  there  is  a  heavier  section  near 
the  tail  than  the  head,  the  fact  that  the  instrument  is  to  be  used 
in  all  positions  kept  out  any  tendency  to  follow  the  well-known 
Thomas  form. 

Of  course  strict  adherence  to  the  principle  of  setting  the 
micrometer  while  it  is  in  the  same  position  and  supported  in  the 


FIG.  222.  —  Knurled  Nuts  for  Micrometer. 

same  way  that  it  is  to  be  while  taking  measurements  is  neces- 
sary. Checking  back  on  the  measuring  rod  after  taking  an 
important  measure  is  to  be  insisted  upon.  Our  own  use  of  the 
suspended  method,  shown  in  the  photograph,  has  been  satis- 
factory, so  much  so  that  we  feel  it  cannot  be  recommended  too 
highly.  It  not  only  gives  better  results  than  any  other  method 
known  to  us,  but  it  requires  no  "tackle"  except  a  helper's  finger 
or  thumb  placed  against  the  work  at  the  right  spot.  While 
this  method  does  not  secure  the  possibility  of  one  man  taking  a 
measure  by  himself  when  using  the  larger  sizes,  the  helper's  part 
is  an  inert  part;  any  other  support  that  could  be  readily  attached 
to  the  work,  and  movable,  would  do  as  well  as  the  helper's  finger 
or  thumb. 


T 


GAGES  AND  GAGING  SYSTEMS 


207 


A  SHOP  SET  OF  MICROMETER  CALIPERS 

The  half-tone,  Fig.  224,  shows  a  set  of  twelve  Slocomb  microm- 
eter calipers  covering  the  range  of  sizes  which  it  is  usually  desir- 


FIG.  224.  —  Set  of  Shop  Micrometers. 

able  to  determine  with  accuracy  in  the  modern  machine  shop. 
The  range  of  each  caliper  is  i  inch.  The  frames  up  to  6  inches  are 
drop  forged  from  bar  steel,  and  the  larger  sizes  are  steel  casting 
with  openings  in  the  web-like  lattice  work  girders.  •  All  are 
finished  in  black  enamel,  and  those  above  3  inches  are  plainly 


2o8  GAGES  AND  GAGING   SYSTEMS 

marked  with  figures  indicating  their  range.  Where  the  calipers 
are  made  for  metric  measurements  the  figures  run  consecutively 
all  through  the  series,  the  first  starting  at  o  and  going  to  25 
millimeters,  the  second  25  to  50,  and  so  on,  the  last  being  275 
to  300  millimeters.  The  set  as  shown  is  of  course  intended  for 
the  tool-room.  There  are  hooks  above  for  the  workmen's  checks, 
and  a  grooved  board  below  for  a  set  of  end  measures  for  correct- 
ing the  adjustment. 

This  plan  of  having  a  series  of  calipers,  each  complete  in 
itself,  and  each  with  a  range  of  an  inch,  is  one  to  commend  to 
shop  managers,  both  because  a  number  of  micrometers  are  some- 
times needed  by  the  different  men  at  the  same  time,  and  because 
no  caliper  should  be  very  much  larger  than  the  size  it  is  to  be 
used  for. 

PRACTICAL  SHOP  USE  OF  MICROMETERS 

A  lathe  hand  of  indifferent  ability  will  work  to  within  a  thou- 
sandth of  an  inch  of  size  if  provided  with  a  rigid  caliper  accurately 
set.  The  average  machinist,  with  the  same  gage  and  in  the 
same  time,  can  work  to  within  a  ten -thousandth  of  a  size,  though 
requiring  more  time.  These  men  could  have  nowhere  near 
approached  these  limits  with  any  degree  of  certainty  using  the 
ordinary  caliper.  Now  the  question  naturally  arises  in  the  mind 
of  the  foreman  alive  to  the  economic  possibilities  of  his  position, 
whether  or  not  a  caliper  of  the  necessary  rigidity  and  accuracy 
could  be  furnished  for  general  use  in  a  shop  at  a  reasonable  cost? 
Limit  gages  are  of  course  out  of  the  question,  for  it  would  be 
beyond  reason  to  expect  a  gage  or  several  gages  for  every  size 
used  in  a  shop.  The  micrometers,  however,  fill  the  bill  admirably, 
except  for  the  expense  of  providing  them  for  general  use  in  a 
large  shop,  and  the  fact  that  the  treatment  they  received  —  in 
a  majority  of  cases  —  would  not  be  such  that  they  could  be  called 
instruments  of  precision  very  long. 

The  accompanying  sketch,  Fig.  225,  is  of  an  adjustable  snap 
gage  that  has  been  used  several  years  as  part  of  a  shop  system 
of  measurements,  and  has  been  found  very  satisfactory.  These 
gages  can  be  made  at  very  small  cost,  especially  if  a  number  of 
them  be  made  at  the  same  time.  The  one  shown  here  will  take 
in  anything  up  to  3  J  inches,  the  size  of  a  gage  most  used  in  gen- 
eral lathe  work.  The  frame  is  of  cast  steel,  very  light  and  rigid; 


GAGES  AND  GAGING   SYSTEMS  209 

the  rod  and  screw  are  T5g-  inch  in  diameter,  the  latter  having  20 
threads  per  inch  and  locked  when  adjusted  by  the  thumb-screw 
shown.  We  experienced  no  difficulty  in  making  the  rod  and 
screw  come  exactly  in  line.  It  was  done  in  the  following  manner: 
The  holes  were  drilled  in  the  lathe  centers  and  then  split  with  a 
hack-saw,  whose  soft  back  had  been  cut  down  until  it  would 
pass  through  the  holes.  The  holes  for  the  thumb-screws  were 
drilled  next,  the  top  half  to  the  whole  diameter  of  the  screw, 
and  the  bottom  half  tapped.  A  cast-iron  sleeve,  i^  inches  long 
and  |  inch  diameter,  was  then  made  to  fit  snugly  over  the  shank 
of  the  tap,  which  had  been  shortened  by  cutting  off  the  square 
end.  The  shank  was  entered  one  half  the  length  of  the  sleeve 
and  tap  and  fitted  with  a  pin.  The  hole  for  the  adjustment 


FIG.  225.  —  Adjustable  Snap  Gage. 

screw  was  then  tapped  from  the  inside  of  the  gage  outward,  the 
shank  end  of  the  tap  being  supported  in  line  by  a  rod  passed 
through  the  other  hole  into  the  sleeve  and  rigidly  clamped  by 
the  thumb-screw.  The  tap  was  turned  by  a  small  bar  fitting 
into  holes  drilled  around  the  sleeve.  The  ends  of  the  rod  and 
screw  are  hardened  and  ground. 

Under  the  system  that  has  been  employed  and  found  so 
satisfactory  we  used  o.i  inch  square  steel  wire  for  " points,"  as 
the  men  called  them.  If  a  man  had  certain  sizes  to  turn  that 
had  to  be  quite  accurate,  he  would  cut  off  pieces  of  this  wire 
about  the  length  required,  stamp  the  size  on  it  and  round  and 
taper  the  ends  so  that  they  were  about  ^V  incn  in  diameter. 
These  points  he  made  approximately  to  size,  and  then  gave  them 
to  the  foreman,  who  tested  them  with  a  vernier  caliper  in  his 
office,  fitting  each  with  a  rub  or  two  of  the  file,  or  perhaps  a  blow 


210 


GAGES  AND   GAGING   SYSTEMS 


of  the  hammer  on  a  small  anvil  beside  the  instrument,  to  bring 
it  up  to  size.  It  is  then  a  simple  matter  when  the  work  is  roughed 
down  nearly  to  size  to  quickly  and  accurately  set  the  snap  gage 
to,  the  point,  making  practically  a  solid  gage.  These  "points" 
are  very  quickly  made,  and  can  of  course  be  kept  for  future  use. 
A  man  seldom  requires  more  than  the  suggestion  that  he  could 
get  his  points  ready  while  his  machine  was  running  before  he 
made  a  practice  of  doing  so.  For  sizes  over  10  inches  we  used 
a  piece  of  broom  handle  or  other  wood,  with  a  pointed  wood  in 
either  end,  flattened  for  wrench. 

When  extreme  accuracy  was  necessary  in  the  smaller  sizes, 
a  small  piece  of  wood  was  drilled  out  and  pressed  over  the  wire 
to  keep  the  heat  of  the  fingers  from  expanding  the  gages  while 
setting.  These  "points"  cannot  be  beaten  for  inside  gages, 


FIG.  226.  —  Outside  and  Inside  Micrometer. 

especially  in  getting  the  size  of  a  hole  already  bored,  when  it  is 
necessary  to  turn  a  piece  to  fit  it  exactly. 

Besides  this  snap  gage,  we  have  a  number  of  the  regulation 
micrometer  calipers  of  all  sizes  in  the  tool-room,  and  accessible 
to  any  one  competent  to  use  them;  but  it  has  been  noticed  that 
it  was  not  long  before  there  was  hardly  any  call  for  them  even 
by  our  best  workmen,  after  they  had  become  accustomed  to  the 
new  system.  We  have  never  known  a  machinist  who  had  tried 
the  system  but  who  was  in  love  with  it,  and  besides  producing 
the  work  within  the  desired  limits  we  found  the  total  time  con- 
sumed much  shortened. 

AN  OUTSIDE  AND  INSIDE  MICROMETER 

The  half-tone  226  shows  a  micrometer  designed  and  pat- 
ented by  Frank  6.  Marbach,  Medina,  Ohio,  for  both  outside 
and  inside  measurements,  its  range  being  from  o  to  I  inch, 


GAGES  AND  GAGING   SYSTEMS 


211 


and  for  the  latter  from  f  to  if  inches.  The  thimble  of  this 
instrument  has  the  usual  graduations  upon  its  periphery,  but 
the  graduations  for  the  inch  movement  are  placed  upon  the  beam 
instead  of  on  the  hub  of  the  head,  rotating  with  the  thimble 
while  the  usual  spindle  is  replaced  by  a  threaded  shank  affixed 
to  the  movable  jaw.  To  compensate  for  the  least  motion  between 
the  nut  (which  is  adjustable)  and  the  spindle,  two  zero  lines 
about  1  inch  apart  are  placed  upon  the  hub,  and  the  reading 
for  the  outside  and  inside  measurements  are  taken  from  different 
lines,  one  being  stamped  "Out,"  and  the  other  "  In."  The  upper 


FIGS.  227,  228,  and  229.  —  Micrometer  Scribing  Block. 


part  of  the  beam  is  graduated  from  zero  to  zero,  and  the  lower 
row  of  graduations  giving  inside  readings  starts  at  625.  While 
the  tool  shown  corners  but  an  inch  travel,  it  is  obvious  that  by 
increasing  the  length  of  the  beam  and  making  the  jaw  —  which 
is  now  fixed  —  adjustable  by  inches,  the  caliper  could  be  made 
to  cover  a  range  of,  say,  6  inches  or  more. 

MICROMETER  SCRIBING  BLOCK 

Sketches  in  Figs.  227,  228,  229  show  a  very  useful  tool,  a 
micrometer  scribing  block.  It  has  an  easy  and  fine  adjustment 
for  accurate  lining  out,  but  its  chief  advantage  over  the  ordinary 


212  GAGES  AND  GAGING   SYSTEMS 

scribing  block  lies  in  its  use  as  a  hight  gage,  as  differences  are 
read  direct,  dispensing  with  paper  or  sheet  gages,  or  in  fact  any 
gage.  Its  main  parts  are  base  A,  screw  B,  nut  C,  sleeve  D,  and 
scriber  E.  The  nut  has  a  long  bearing  on  the  screw,  and  has 
a  slit  sawed  up  about  a  half  inch  in  length.  Screw  B  has  a  key- 
way  in  it  in  which  fits  pin  F,  which  stops  the  sleeve  from  rotating. 
Sleeve  D  also  is  slit.  Nut  C  is  graduated  with  forty  divisions, 
and  rests  against  a  line  on  the  sleeve.  The  spring  keeps  spring 
D  up  against  the  nut.  To  lock  the  sleeve  to  the  screw,  knurled 
screw  G  is  turned,  which  tightens  the  sleeve  on  the  nut,  which 
in  turn  is  tightened  on  the  screw. 

MICROMETER  SCALES 

Having  seen  a  set  of  scales  like  those  shown  in  Figs.  230  to 
234,  in  use  for  a  long  time  by  a  workman  in  the  shop,  we  con- 
cluded they  would  be  of  interest  to  others,  and  describe  them  as 
follows:  The  positiveness  and  accuracy  found  in  their  use  cer- 
tainly justify  the  employment  of  the  term  micrometer  in  naming 
them. 

They  are  tapering  steel  scales  graduated  on  both  sides,  one 
side  having  divisions  of  hundreds,  and  the  other  of  sixty-fourths. 
Measurements  can  be  taken  very  quickly,  for  the  instant  contact 
is  made  between  the  two  points  the  reading  is  obtained;  there 
is  no  yielding,  as  with  a  common,  a  vernier,  or  even  a  micrometer 
caliper.  The  different  scales  in  the  set  make  a  series  of  over- 
lapping measuring  bars  about  TV  inch  thick,  one  scale  supple- 
menting the  other  after  the  manner  of  a  set  of  taper  broaches 
or  reamers;  and  a  surplus  at  the  ends  in  excess  of  the  graduated 
part  of  the  scale  is  left  for  convenient  handling. 

Take,  for  example,  the  scale  shown  in  Fig.  230,  and  we  have 
two  divisions  on  the  left  hand,  from  26  to  28,  representing  the 
distance  required  to  increase  the  width  of  the  scale  from  26  to 
28,  and  then  subdivisions  (common  to  the  whole  scale  in  the 
practice,  but  omitted  in  the  drawings)  give  an  easy  advance  in 
thousandths,  making  the  latter  more  easily  visible  than  sixty- 
fourths  on  the  usual  scale.  Entering  the  scale,  as  shown  in  Fig. 
234,  a  much  more  certain  measurement  of  .29  is  obtained  than 
would  be  possible  with  the  ordinary  scale  held  with  lines  opposite 
the  edges  of  the  opening.  The  lines  on  the  scale  are  made  at 


GAGES  AND  GAGING  SYSTEMS 


213 


right  angles  to  the  lower  sides,  as  shown  in  the  cuts.     It  will 
be  seen  that  the  taper  is  \  inch  to  the  foot. 

In  Figs.  235  and  236,  let  A  be  a  part  of  the  saddle  on  a  planer 
or  shaper,  B  the  cross-head,  and  C  a  bar  clamped  by  D  to  the 
latter.  The  bar  C  is  clamped  to  the  top  of  the  cross-head  in 
Fig.  236,  instead  of  on  the  front,  as  in  Fig.  235,  and  the  scale  is 


,71 

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Micrometer  Scales 


FIGS.  230  to  236.  —  Micrometer  Scales. 


used  horizontally.  If  a  dividing  tool  TV  inch  thick  has  made  a 
cut  into  a  piece  of  metal,  and  it  is  intended  to  make  the  groove 
in  the  work  T%  inch  wide,  then  instead  of  measuring  on  the  work 
or  the  tool,  a  piece  C  is  brought  up  and  clamped  to  the  cross- 
head,  and  the  ^-inch  measurement  taken  with  the  scale  as  shown 
in  Figs.  235  and  236. 

Fig.  237  illustrates  an  accurate  and  convenient  way  of  setting 
a  surface  gage  point  to  hight.     A  piece  of  work  shown  in  Fig. 


214 


GAGES  AND  GAGING  SYSTEMS 


238  laid  out  in  this  way  and  tested  up  by  the  points,  and  bored 
out  on  lathe  face-plate,  came  perfect. 

Fig.  239  shows  a  positive  method  of  intersecting  lines,  one 
at  K  getting  a  distance  from  the  edge  of  the  work  by  means  of 


FIG.  237.  —  Setting  a  Surface  Gage. 


a  block  clamped  as  shown ;  and  one  at  L  giving  a  point  on  a  line 
any  required  distance  from  the  stud  M. 

A  piece  of  metal  is  to  be  planed,  say,  from  i^  to  i  inch  thick- 
ness: Slide  the  scale  between  the  tool  and  the  planer  bed  to  i^ 


FIG.  238.  —  Work  Laid  Out. 

and  rough-cut  one  side,  turn  the  work  over,  set  the  tool  to  1.02 
and  do  the  same  to  that  side.  Then  if  .01  is  right  for  a  finishing 
cut,  set  the  tool  to  i.oi  for  one  side  and  to  i  inch  for  the  other; 
the  work  being  fastened  to  the  planer  bed.  Fig.  240  gives  an 


GAGES  AND  GAGING  SYSTEMS 


215 


idea  of  the  use  of  two  scales  together,  giving  here  2.756  inches. 
Decimal  and  common  fractions  are  easily  convertible  by  reversing 
the  scale;  and  once  determine  the  number  of  thousandths  required 


FIG.  239.  —  Method  of  Intersecting  Lines. 

for  an  easy,  tight,  driving  or  scraping  fit,  a  cut  can  be  taken 
with  extreme  accuracy  for  either  by  the  use  of  these  scales. 

A  MICROMETER  GEAR  TOOTH  GAGE 

Fig.  241  clearly  shows  all  that  is  essential  of  a  recently  de- 
vised gage,  and  also  the  application  of  it.     This  gage  is  pat- 


I      I      I       I       I    Ml    M   MM      I       I       I   I   I      I 

H       ii  : 


FIG.  240.  —  Two  Micrometer  Scales  Together. 

ented  by  J.  Boulet,  Beverly,  Mass.  As  will  be  seen,  its  sole 
function  is  the  measuring  of  the  thickness  of  spur  gear  teeth 
at  the  pitch  line,  for  the  purpose  of  ascertaining  their  accuracy, 
and  discovering  any  errors  in  the  cutting.  The  jaw  at  the  right 


2l6 


GAGES  AND   GAGING   SYSTEMS 


is  fixed  to  the  bar  of  the  instrument,  while  the  other  jaw  is  moved 
in  either  direction  by  the  micrometer  screw,  the  nut  of  which  is 
fixed  to  the  other  end  of  the  bar.  By  this  means  the  thickness 
of  the  tooth  may  evidently  be  measured  as  accurately  as  in  any 
other  application  of  the  micrometer,  provided  the  points  of  the 
measuring  jaws  are  brought  to  the  proper  location  on  each  side 
of  the  tooth.  The  positions  of  the  jaws  relatively  to  the  tooth 
are  determined  by  the  central  vertical  micrometer  screw.  The 
point  of  this  screw  is  always  central  relatively  to  the  jaws,  and 


FlG.  241.  —  Micrometer  Gear  Tooth  Gage. 

the  micrometer  adjustment  brings  the  jaws  to  the  correct  hight 
for  the  pitch  line,  according  to  the  pitch  of  the  gear  tooth  to  be 
measured.  To  keep  the  vertical  screw  always  central  between 
the  jaws,  it  must  evidently  move  in  the  same  direction  as  the 
movable  jaw,  but  at  half  the  speed.  The  small  horizontal  screw 
which  moves  the  block  which  carries  the  central  or  depth  mi- 
crometer is  a  continuation  of  the  screw  which  moves  the  thick- 
ness measuring  jaw,  but  the  pitch  of  the  screw  is  only  one  half 
that  of  the  larger  screw,  and  the  pitch  is  also  reversed.  Thus, 
if  the  principal  screw  is  forty  to  the  inch  and  right-handed,  the 
small  screw  for  moving  the  depth  gage  must  be  eighty  to  the 
inch  and  left-handed.  This  instrument  will,  of  course,  do  its 


GAGES  AND  GAGING  SYSTEMS 


217 


work  as  accurately  as  any  other  micrometer,  employing  this 
familiar  means  of  minutely  indicating  the  movements  of  the 
measuring  jaws,  provided  it  is  accurately  made,  which,  of  course, 
it  must  be. 

MICROMETER  ATTACHMENT  FOR  THE  LATHE 
The  sketch,  Fig.  242,  shows  a  device  for  clamping  a  microm- 
eter head  to  the  lathe  bed.  The  inner  side  of  the  45-degree 
angle  is  left  short  so  that  the  fixture  is  not  unnecessarily  high, 
and  also  to  allow  it  to  be  removed  from  the  ways  of  the  lathes 
with  the  fewest  possible  turns  of  the  knurled  head  screw.  The 
micrometer  head  is  held  in  place  by  means  of  a  brass  screw,  so 


FIG.  242.  —  Micrometer  Attachment  for  .Lathe. 

that  it  may  be  readily  removed  if  wanted  for  any  other  purpose. 
When  turning  where  the  distance  from  one  shoulder  to  another 
must  be  very  accurate,  or  where  a  given  amount  is  to  be  faced 
from  a  piece  of  work,  the  fixture  should  be  clamped  so  as  to  allow 
the  carriage,  the  barrel  being  turned,  to  keep  the  micrometer 
spindle  in  contact  with  the  side  of  the  carriage  until  the  required 
distance  has  been  traveled. 

MICROMETER  CALIPER  FOR  MEASURING  THE  RADIUS  OF  SPINDLE 
DRILLS  AND  SIMILAR  PIECES  IMPOSSIBLE  TO  MEASURE  DI- 
RECTLY 

The  principle  of  this  gage  is  shown  in  the  sketch,  Fig.  243. 


As  we  have  a  constant  angle  of  — 


65  degrees,  the  line  will 


218  GAGES  AND   GAGING   SYSTEMS 

always  be  a  fixed  ratio  with  the  correct  radius  of  the  piece  to 
be  measured.  So  we  have  only  to  multiply  the  radius  of  the 
piece  to  be  measured  by  the  constant  1.103  an<^  set  tne  gage  to 
this  amount.  The  constant  is  found  by  the  reckoning: 


=  1.103. 


cos.  25°  0.90631 
To  set  the  caliper  at  zero,  it  is  necessary  to  have  a  measuring 
disk,  say  lo-millimeter  diameter,  then  we  reckon  the  distance, 
Fig.  243,  for  this  disk  as  follows:  5  x  1.103  =  5-5!5'  an<^  a^d  to 
this  r  =  5,  giving  10.515;  to  this  amount  we  set  our  screws,  then 
put  the  disk  between  the  point  of  the  screw  and  the  anvil,  and 
tighten  the  anvil  when  the  gage  is  ready  for  measuring  any 
diameter  up  to  20-millimeter  radius.  For  larger  diameter,  we 


FIG.  243 


make  the  same  arrangements  with  a  measuring  disk  3o-millimeter 
diameter,  and  are  then  able  to  measure  the  radius  of  the  pieces 
up  to  6o-millirneter  diameter. 

This  gage  is  especially  valuable  in  milling  to  the  center  of 
things  where  the  periphery  is  interrupted,  as  in  spindle  drills, 
etc.,  a  section  of  which  is  shown,  Fig.  244. 

Example:  —  To  stake  a  center  of  a  piece  19.5  diameter,  we 
set  the  gage  according  to  the  first  case  and  reckon:  9.75  x  1.103 
—  amount  we  ought  to  read  on  the  micrometer  scale  when  the 
center  has  been  reached.  Fig.  245  shows  the  instrument  with 
the  measuring  disks. 

A  MICROMETER  STOP 

Every  mechanic  knows  when  he  is  facing  a  piece  of  work, 
how  difficult  it  is  to  move  the  lathe  carriage  just  the  right  amount 
when  there  is  a  thousand  or  two  for  the  finishing  cut. 


GAGES  AND  GAGING  SYSTEMS 


219 


The  stop,  Fig.  246,  is  clamped  to  the  lathe  bed  at  any  con- 
venient point,  and  adjusted  to  abut  against  the  carriage,  when 
reading  can  be  taken  and  the  carriage  moved  accurately  any 
distance  within  range  of  the  stop,  in  this  case  i  inch.  It  can 
be  used  for  a  variety  of  work,  such  as  recessing  an  exact  depth 
below  a  finished  surface,  stepping  from  one  surface  to  another 
by  means  of  a  distance  piece  between  stop  and  carnage,  etc. 

Having  a  piece  of  work  on  the  face-plate,  and  after  measuring 
the  location  of  a  hole  just  bored,  it  was  found  to  be  just  one  thou- 


FIGS.  244  and  245.  —  Micrometer  Radius  Gage. 

sandth  out  of  center.  It  was  but  little  work  to  clamp  the  stop 
to  the  face-plate,  take  a  reading  from  the  side  of  the  work,  loosen 
bolts  and  tap  over  the  right  amount  by  measurement. 

TESTING  MACHINE  TOOLS  WITH  A  MICROMETER  CALIPER 

It  is  of  course  obvious  that  the  micrometer  caliper  can  be 
applied  in  many  ways,  and  for  the  purpose  of  making  many  other 
tests  of  the  accuracy  of  machine  tools  besides  those  given  else- 
where in  this  book.  We  present  herewith  a  few  of  these,  and 


220 


GAGES  AND  GAGING  SYSTEMS 


many  others  will  readily  suggest  themselves  as  the  occasion  for 
them  arises.  It  is  often  desirable  to  test  a  drill  press,  to  see 
whether  the  spindle  is  at  right  angles  with  the  table  or  platen. 


FIG.  246.  —  Micrometer  Stop. 

A  test  for  these  is  shown  in  Fig.  247.  A  parallel  strip  or  piece 
of  bar  stock  A  is  clamped  to  the  end  of  the  spindle,  or  if  more 
convenient  to  a  piece  held  in  a  chuck.  On  the  end  of  this  piece, 


FIG.  247.  — Testing  Drill  Press  Table. 

and  near  the  end  of  the  table,  is  clamped  the  caliper,  as  shown. 
A  measurement  is  then  taken  at  B  and  noted,  and  the  spindle 
and  caliper  turned  around  to  the  position  shown  by  the  dotted 
lines,  and  another  measurement  at  C,  when  the  alignment  side- 


GAGES  AND   GAGING   SYSTEMS  221 

ways  may  be  noted.     Two  other  measurements,  one  in  front,  the 
other  at  the  back,  will  complete  this  test. 

Sometimes  it  is  desired  to  know  the  deflection  of  the  platen 
under  the  pressure  of  drilling,  as  of  course  that  affects  the  align- 
ment of  the  machine  and  the  quality  of  the  work  turned  out. 
For  this  purpose  the  caliper  should  be  clamped  by  any  other 
convenient  means,  which  will  readily  suggest  itself,  to  the  slid- 
ing head  of  the  drill  spindle,  and  in  such  a  way  as  not  to  interfere 
with  the  work.  The  caliper  may  be  extended  down  to  measure 
the  table  or  platen  direct  or  two  blocks  on  the  table,  or  to  work 
itself,  as  may  be  most  convenient. 

Before  any  pressure  is  put  on  the  drill  spindle,  a  measurement 
should  be  taken  and  noted;  then  the  drilling  commenced,  and 
after  the  drill  has  started  properly,  the  spindle  stopped  with  the 
feed  still  on  and  another  measurement  taken,  when  the  deflection 
under  working  conditions  may  be  noted. 

When  a  drill  press  is  used  on  one  line  of  work,  it  is  by  this 
means  an  easy  matter  to  throw  the  spindle  out  of  line  just  enough 
to  compensate  for  deflection  and  be  right  under  working  con- 
ditions. 

In  using  the  ordinary  machine  vise,  such  as  we  find  on  the 
planer,  shaper,  and  milling  machine,  we  often  want  to  know 
whether  or  not  the  fixed  jaw  is  square,  or,  in  other  words,  whether 
work  held  against  it  by  the  movable  jaw  will  be  planed  or  milled 
square  and  true  with  that  side.  We  usually  find  it  out  by  putting 
the  work  in  place  and  taking  a  cut  over  it  and  then  trying  it 
with  a  square.  In  Fig.  248  is  shown  what  will  usually  be  found 
a  quicker  and  more  satisfactory  method. 

The  square  A  is  clamped  against  the  solid  jaw  B  by  a  small 
bar  of  brass  or  other  soft  metal  or  stick  of  wood,  as  shown  at  C. 
The  caliper  is  clamped  on  a  tool  shank  held  in  the  shaper  or  on 
the  milling  machine  arbor,  as  the  case  may  be,  and  a  measure- 
ment taken  to  the  edge  of  a  square  blade,  as  shown  at  D;  then  by 
moving  the  slide  another  measurement  is  taken,  as  shown  by 
the  dotted  lines  at  E.  This  of  course  will  show  at  once  whether 
the  jaw  is  at  right  angles  with  the  machine  slide,  which  is  neces- 
sary to  produce  square  work. 

When  the  work  is  supported  on  parallel  strips  or  directly  on 
bottom  F  of  the  vise,  to  find  whether  that  face  is-  parallel  with 
the  slide  of  the  machine,  it  is  of  course  only  necessary  to  dispense 


222 


GAGES  AND   GAGING   SYSTEMS 


with  the  square,  and  opening  the  vise  to  its  full  extent,  apply 
the  caliper  direct  to  that  surface  at  not  less  than  four  points, 
or  at  the  extreme  corners,  which  will  show  at  once  how  the  work 
is  expected  to  come  out. 

It  is  often  desired  to  set  the  vertical  tool  slide  of  a  shaper 
or  planer  nearer  vertical,  or  at  right  angles  to  the  platen,  than 
may  be  done  by  the  graduations.  If  a  machine  vise  with  a 
square  jaw  be  at  hand,  it  may  be  done,  as  shown  at  Fig.  249,  in 
which  the  parallel  strip  A  is  held  against  the  jaw  B,  as  in  the 
square  in  Fig.  248;  then  by  clamping  the  caliper  to  a  tool  shank 


FIG.  248.  —  Testing  Machine  Vise. 

held  on  the  slide,  measurements  taken  at  both  ends  of  the  parallel 
strip  by  running  the  slide  up  and  down  will  show  whether  the 
slide  is  in  its  proper  position  or  not. 

This  also  affords  a  ready  means  of  setting  the  head  exactly 
at  any  desired  slight  inclination,  so  as  to  produce  slightly  tapering 
work  of  definite  proportions.  Say,  for  instance,  it  is  desired  to 
plane  down  a  surface  nearly  vertical,  but  with  an  inclination  of, 
say,  .005  inch  in  4  inches.  In  such  a  case  it  would  be  necessary 
to  make  two  marks  upon  the  piece  A,  Fig.  249,  four  inches  apart, 
then  set  the  head  so  that  the  micrometer  would  show  the  required 
difference  of  .005  inch  when  applied  at  the  two  different  points 
thus  marked. 


GAGES  AND  GAGING  SYSTEMS 


223 


Another  way  of  testing  which  would  usually  be  much  more 
handy  for  the  planer,  especially  where  the  vise  is  not  so  much 
used,  is  to  clamp  to  the  platen  a  square  with  its  blade  standing 
vertical  and  crossways  to  the  platen,  and  make  the  measurements 
to  the  edge  of  this  blade,  as  shown  on  the  parallel  strip  held  in 
the  vise  in  Fig.  249. 

The  truth  of  the  two  screws  that  operate  the  cross-rail  of  a 
planer,  which  is  all  that  it  is  usually  desired  to  know,  may  be  very 
easily  and  quickly  tested  by  clamping  the  caliper  to  the  end  of  a 
long  bar  of  steel,  such  as  is  used  for  tools  and  clamped  in  the  tool- 


FIG.  249.  —  Testing  Machine  Vise. 

block.  Starting  with  the  cross-rail  down  near  the  platen,  make 
a  measurement  near  one  edge,  then  run  the  saddle  and  tool-block 
to  the  other  side  and  measure  again.  By  now  raising  the  cross- 
rail,  say  6  inches,  and  letting  down  the  bar  carrying  the  caliper, 
measure  again  on  both  edges  of  the  platen.  Continue  this  opera- 
tion until  the  full  hight  of  the  housing  is  reached,  and  if  a  record 
of  the  readings  has  been  made,  it  is  easy  to  see  at  a  glance  how 
near  alike  the  screws  are,  and  if  there  be  an  error  just  how  it  is, 
and  how  much. 

Most  milling  machines,  and  especially  universal  ones,  have 
graduated  dials  reading  to  thousandths  of  an  inch  on  most  all 


224  GAGES  AND   GAGING   SYSTEMS 

the  slides.  On  such  machines  the  caliper,  as  shown,  used  in  these 
various  tests,  is  not  of  so  much  advantage,  as  the  reading  may 
be  taken  direct  from  the  machine  itself  when  testing  the  platen 
for  truth  in  both  ways  with  the  cutter  arbor  and  spindle.  But 
on  such  machines  as  do  not  have  these  graduated  dials,  the 
clipper  method  of  testing  and  for  setting  the  work  in  the  proper 
way  upon  them  will  be  found  both  quick  and  handy,  and  after 
the  habit  of  using  it  is  acquired,  quick  and  accurate  setting  of 
work  will  be  greatly  facilitated. 

There  are  test  indicators  on  the  market  which  read  to  thou- 
sandths of  an  inch  over  quite  a  range,  and  some  of  them  would 
answer  the  purpose  of  these  tests  much  better  than  the  micrometer 
caliper,  as  they  would  be  much  quicker  and  would  in  themselves 
take  care  that  the  contact  pressure  is  the  same  at  all  readings. 
Special  indicators  have  not  found  a  place  in  this  article  for  the 
reason  that  they  are  special  tools,  while  the  object  of  this  is  to 
show  how  the  tests  may  be  made  cheaply  and  quickly  without 
special  tools. 

TESTING  THE  ACCURACY  OF  A  LATHE  WITHOUT  SPECIAL  TOOLS 

When  the  new  lathe  comes  into  the  shop,  and  sometimes  in 
the  case  of  an  older  one,  it  is  desirable  to  know  about  how  true 
it  is,  or  more  accurately  speaking,  how  its  various  parts  line  up 
one  with  the  other.  Sometimes  it  is  not  merely  desirable  to 
test  the  lathe,  but  may  be  necessary,  and  perhaps  if  it  were  not 
considered  to  be,  and  usually  made,  such  an  expensive  job,  more 
lathes  would  be  tested  and  made  right  when  found  not  to  be 
true,  and  very  likely  a  great  deal  of  time  would  be  saved  by  the 
ability  to  turn  out  better  work. 

There  are  many  ways  to  test  lathes  by  the  use  of  specially 
devised  indicators  and  micrometers,  and  good  straight-edges 
and  round  true  arbors;  and  a  good  many  articles  have  been 
published  describing  these  tools  and  methods  which  are  well 
enough  for  manufacturers  of  lathes,  but  not  at  all  adapted  to 
the  needs  of  the  lathe  users.  What  we  want  to  consider  now 
is  how  to  do  the  job  without  special  tools  or  fixtures,  and  with 
just  the  ordinary  stuff  that  is  found  kicking  around  the  floor  of 
almost  any  jobbing  shop,  and  can  be  easily  had  in  any  other 
kind  of  a  shop.  At  this  date  there  are  not  many  machine  shops 


GAGES  AND  GAGING   SYSTEMS  225 

in  this  country  which  do  not  possess  at  least  one  ordinary  i-inch 
micrometer  caliper,  and  this  we  will  use  in  the  testing  of  lathes. 
Shops  which  do  not  possess  such  a  caliper  do  not  usually  want 
to  test  lathes.  The  caliper  is  not  absolutely  necessary,  however, 
and  the  job  can  be  done  without  it,  but  can  be  done  more  quickly 
by  using  the  caliper,  which  will  not  only  show  when  a  thing  is  out, 
but  also  just  how  much,  which  is  exactly  what  we  want  to  know. 

Perhaps  it  will  be  well  to  begin  with  the  foot-stock  and  see 
if  its  spindle  is  parallel  with  the  ways  or  shears  of  the  bed,  a 
necessary  thing  if  good  work  is  to  be  done. 

For  this  test  we  will  consider  a  lathe  of  about  16  inches  swing 
and  6-foot  bed.  The  first  thing  we  will  need  is  a  piece  of  centered 
shaft,  or  an  arbor,  about  2  inches  diameter,  4  feet  long.  It  need 
not  be  either  straight  or  round,  but  should  be  well  centered  and 
square  up  true  on  the  ends.  Put  this  arbor  on  the  centers  with 


FIG.  250.  —  Testing  Lathe. 

the  foot-stock  spindle  clear  back.  Make  some  kind  of  a  mark, 
as  with  chalk,  near  the  tail  center  end  of  the  arbor,  as  at  A, 
Fig.  250. 

In  the  tool-post  of  the  lathe  mount  the  i-inch  micrometer 
caliper,  as  shown  in  Fig.  251,  with  the  thimble  end  to  the  work. 
This  may  be  done  by  bending  a  tool  shank  or  piece  of  iron,  as 
at  A,  Fig.  251,  and  the  caliper  can  be  held  in  place  upon  it  by 
almost  any  kind  of  a  clamp  that  comes  handy,  such  as  B.  By 
moving  the  carriage  and  tool-block,  bring  the  thimble  end  of  the 
caliper  near  the  mark  A  on  the  arbor  in  Fig.  250,  open  the  caliper 
to  bring  the  thimble  in  contact  with  the  arbor  —  though  it  would 
be  a  good  plan  perhaps  to  interpose  a  piece  of  paper  between  the 
caliper  and  arbor,  which  may  be  pulled  between  them  in  order 
to  always  get  about  the  same  contact.  When  the  proper  contact 
is  made  note  the  reading  and  back  off  the  caliper  by  turning 
the  thimble,  but  do  not  move  the  tool-block.  Now  loosen  the 
foot-block,  and  run  the  spindle  out  to  near  the  end  of  the  screw, 


226 


GAGES   AND   GAGING   SYSTEMS 


and  clamp  again;  then  measure  again  just  as  before,  and  if  the 
two  readings  agree,  the  tail  spindle  is  in  line  sidewise.  The 
caliper  should  now  be  changed  to  the  position  shown  in  Fig.  252, 
and  the  two  measurements  taken  on  top  of  the  arbor  the  same 
as  taken  at  the  side.  The  mark  A  is  now  turned  upward,  since 
we  are  assuming  that  the  arbor  is  not  true,  and  this  enables  us 
to  measure  from  the  same  spot  for  each  measurement  of  a  given 
test. 

Perhaps  the  thing  to  do  next  is  to  test  the  truth  of  the  live 
center.  Measure  to  the  spot  on  the  arbor  near  the  live  center, 
either  from  the  side  or  top,  then  turn  the  spindle,  say  quarter 
way  around,  holding  the  arbor  in  the  original  position,  and  measure 
again ;  repeat  this  about  four  times,  and  if  all  the  readings  agree 
the  center  is  about  right. 


FIG.  251.  —  Micrometer  Test. 

A  way  to  test  the  center  hole  is  to  put  the  center  in  place, 
being  careful  to  have  it  clean,  and  turn  or  grind  it  true;  then 
remove  and  put  it  back  again  turned  half  way  around  from  the 
first  position,  when  the  error  of  the  hole,  if  there  be  any,  will 
be  double  and  may  be  more  rapidly  measured.  Sometimes  the 
front  and  back  end  of  this  hole  are  not  true  with  each  other, 
and  in  this  case  about  the  only  way  to  test  or  find  out  how  much 
it  is  out  is -to  fit  a  piece  to  the  hole,  having  a  straight  end,  which, 
in  this  case,  should  be  both  true  with  the  taper  shank  and  straight. 
By  putting  this  in  place  and  measuring  with  the  caliper  held  as 
in  Fig.  251  at  both  ends  and  turning  the  spindle,  it  may  be  seen 
at  once  whether  the  hole  is  in  its  proper  place. 

Next  we  will  line  up  the  head  and  tail  centers.  Put  the  caliper 
in  position,  Fig.  251,  and  measure  to  the  marked  spot  on  the 


GAGES  AND  GAGING   SYSTEMS 


227 


arbor,  then  turn  the  arbor  end  for  end  and  run  the  carriage 
along  without  changing  the  cross-slide,  and  measure  again.  If 
the  two  readings  agree,  all  right;  if  not,  adjust  the  foot-stock 
until  they  do  agree,  when  the  center  will  be  in  line  with  the  shears. 

To  find  if  the  centers  are  the  same  hight,  place  the  caliper 
in  position,  Fig.  252,  and  measure  near  each  center  by  reversing 
the  arbor  as  before. 

To  find  whether  the  live  spindle  is  in  line  with  the  centers 
and  shears,  clamp  a  parallel  strip  or  rough  piece  of  bar  iron, 
such  as  B,  Fig.  250,  on  the  arbor  near  its  end,  and  on  that  clamp 
the  caliper  as  shown.  Then  with  the  largest  face-plate  in  the 
spindle,  and  a  mark  on  the  plate  (as  it  is  not  assumed  to  run  true 


FIG.  252. —  Micrometer  Test. 

at  all),  measure  to  the  plate  with  the  mark  at  the  top  and  again 
at  the  bottom  by  turning  both  the  spindle  and  the  arbor.  Any 
difference  in  the  readings  will  show  at  once  which  way  the  spindle 
inclines  vertically.  Repeat  this  operation  by  measuring  both  at 
the  front  and  at  the  back,  by  which  the  alignment  laterally  with 
the  shears  may  be  noted. 

To  find  whether  the  cross-slide  is  at  right  angles  with  the 
spindle  and  shears:  If  a  good  straight-edge  be  at  hand,  one  way 
is  to  take  a  cut  over  the  large  face-plate,  and  apply  the  straight- 
edge, when,  if  the  spindle  is  in  line  with  the  shears  and  the  plate 
is  flat,  the  cross-slide  will  be  shown  to  be  at  right  angles.  But 
perhaps  it  is  not  convenient  to  take  a  cut  right  over  the  plate, 
and  so  we  will  consider  a  way  of  doing  it  without  any  cutting  at 


228 


GAGES  AND  GAGING  SYSTEMS 


all.  Mount  the  caliper  on  a  tool  shank,  as  shown  in  plan  in  Fig. 
253,  with  the  thimble  pointing  to  the  face-plate.  Most  tool- 
blocks  will  not  go  far  with  the  thimble  pointing  to  the  face-plate. 
Most  tool-blocks  will  not  go  far  back  of  the  center,  so  the  caliper 
should  be  mounted  somewhat  in  front  of  the  tool -post,  as  shown, 
so  that  it  may  travel  an  equal  distance  each  side  of  the  center, 
and  should  go  as  far  as  possible  from  it  in  each  direction.  Measure 
to  a  mark  on  the  face-plate,  as  shown  in  full  lines  at  A,  then 
back  of  the  thimble,  and  move  the  tool-block  and  caliper  to  the 
position  shown  by  the  dotted  lines  at  B.  Turn  the  spindle  to 
bring  the  mark  on  the  plate  to  that  side  and  measure  again, 


FIG.  253.  —  Micrometer  Test. 

and  if  the  two  readings  agree  the  cross-slide  is  at  right  angles 
with  the  spindle  and  also  with  the  shears,  if  the  spindle  is  properly 
in  line;  if  not,  its  position  may  easily  be  found  by  noting  the 
alignment  of  the  spindle,  as  shown  by  the  preceding  test. 

It  may  be  preferable  to  make  this  last-named  test  with  the 
micrometer  arranged  as  in  Fig.  250,  except  that  the  piece  B 
should  then  be  nearer  the  middle  of  the  length  of  the  arbor.  A 
piece  of  any  convenient  form  can  be  held  in  the  tool-post  and 
brought  into  contact  position  with  the  micrometer,  first  in  front 
and  then  at  the  back  of  the  arbor,  rotating  the  latter  upon  the 
center  to  bring  the  micrometer  into  position,  and  moving  the 
cross-slide  by  the  screw.  This  method  has  the  advantage  of 


GAGES  AND  GAGING   SYSTEMS  229 

eliminating  any  error  that  might  arise  from  end  motion  of  the 
spindle  when  rotating  it;  but  it  is  to  be  observed  that  it  shows 
only  whether  the  cross-slide  is  square  with  the  lines  of  the  centers, 
and  nothing  more  than  that.  If,  however,  the  centers  have 
previously  been  lined  up  with  the  shears  by  the  method  described, 
then  this  last-named  test  also  shows  whether  the  cross-slide  is 
square  with  the  shears  or  not.  And  if  the  spindle  has  been 
previously  lined  up  with  the  line  of  centers,  as  previously  described, 
then  this  last-named  test  shows  also  whether  or  not  the  cross- 
slide  is  square  with  the  spindle. 

It  will  be  seen  that  the  micrometer  caliper  is  not  absolutely 
necessary  for  any  of  these  tests,  as  by  the  use  of  a  common  cap 
screw,  fitted  rather  snugly  in  the  piece  held  in  the  tool-post  and 
on  the  arbor,  all  the  tests  may  be  made,  and  perhaps  just  as 
accurately  as  with  the  caliper,  but  with  the  disadvantage  of  not 
indicating  how  much  the  various  points  are  out  of  position. 

The  method  of  testing  the  lathe  is  not  given  with  the  belief 
that  it  is  the  very  best  that  can  be  used,  but  it  is  a  very  cheap 
and  simple  method  covering  most  of  the  points  desirable  to  be 
tested,  and  at  a  cost  that  will  not  prohibit  its  frequent  use. 

The  use  of  the  end  of  the  thimble  of  the  micrometer  caliper 
is  not  a  new  idea  at  all,  though  perhaps  it  is  as  applied  in  this 
way  and  for  this  purpose.  One  of  the  very  early  calipers,  made 
in  France,  and  illustrated  in  the  American^  Machinist  some  years 
ago,  had  a  hardened  contact  point  on  the  end  of  the  thimble, 
and  another  extended  from  the  ordinary  anvil;  the  caliper  was 
intended  for  internal  measurements  as  well  as  for  the  ordinary 
outside  work. 

A  NEW  SWEDISH  COMBINATION  GAGING  SYSTEM 

An  interesting  and  rather  unusual  set  of  gages  of  Swedish 
origin  has  been  brought  out  by  the  Grbnkvist  Drill  Chuck  Company 
of  Jersey  City  under  the  name  of  the  Johansson  Gages.  The  re- 
markable features  of  this  system  are  the  exquisite  finish  of  the 
surfaces  which  enables  the  use  of  them  either  singly  or  in  multiple 
by  the  simple  process  of  wringing  them  together.  In  Fig.  254  the 
complete  set  of  gages  is  shown  in  its  box,  which  is  10  x  15!  inches 
and  weighs  yj  pounds.  In  the  various  series  in  this  case  are  gages 
ranging  from  o.iooi  to  0.1009  inches  in  thickness  rising  by 
o.oooi  up  to  gages  of  2  to  4  inches  rising  by  i  inch. 


GAGES  AND  GAGING   SYSTEMS 


231 


It  will  readily  be  seen  that  by  taking  proper  selections  of  these 
gages  and  wringing  them  together  a  complete  gage  can  be  made 
of  any  size  desired.  It  is  estimated  that  at  least  80,000  different 
sizes  may  be  made  and  in  all  probability  this  is  a  low  estimate. 
No  thickness  has  yet  been  discovered  which  cannot  be  accom- 
plished by  the  various  combinations,  and  the  majority  of  the  points 
can  be  reached  by  several  different  combinations  enabling  an  accu- 
rate checking  up  in  case  of  doubt. 

Fig.  255  shows  22  gages  supporting  each  other  horizontally. 
It  gives  the  best  idea  of  the  manner  in  which  they  are  to  be  used, 


FIG.  255.  —  Twenty-two  Gages  Support  Each  Other. 

and  yet  when  built  up  in  this  manner  the  feel  of  the  gage  is  the 
same  as  of  a  solid  piece  and  this  holds  for  any  combination. 

Fig.  256  shows  one  large  piece  and  two  small  pieces  aggregat- 
ing the  same  measurement.  On  the  outside  faces  two  more  pieces 
are  wrung  on,  lapping  half  on  the  single  piece  and  half  on  the  built- 
up  piece.  The  whole  may  be  supported  by  any  one  of  the  pieces 
without  falling  apart.  An  indefinite  number  of  combinations 
may  be  successively  subjected  to  this  test,  which,  as  regards  the 
accuracy  of  the  pieces,  is  of  course  almost  absolute. 

Fig.  257  shows  the  way  these  gages  are  used  in  multiple  for 
plug  gages.  The  two  outside  pieces  are  lapped  to  a  circle;  the 
two  wrung  together  will  measure  a  half-inch  hole.  Any  of  the 
flat  gages  can  be  used  between  the  outside  pieces  to  make  a  gage 
for  any  size  of  hole  desired.  Fig.  258  again  shows  a  one-inch 
snap  gage  with  a  built-up  piece  in  it  -0.5  plus  0.2  plus  0.050 
plus  0.150  plus  o.ioo. 

Though  the  adhesion  of  these  gages  is  the  same  as  if  they 


o  W 

cxO 


o  o 


GAGES  AND  GAGING   SYSTEMS  233 

were  strongly  magnetized,  yet  as  a  matter  of  fact  they  are  not 
magnetized  at  all.  They  can  only  be  held  together  when  wrung 
so  that  the  air  is  excluded.  Yet  the  tension  of  pieces  which  have 
been  wrung  together  is  greater  than  that  of  air  pressure,  so  that 
it  is  evident  that  some  molecular  attraction  is  combined  with  the 
force  of  the  air  pressure  in  holding  them. 

In  brief,  then,  we  are  furnished  with  a  complete  set  of  gages 
enabling  the  mechanic  to  secure  any  size  that  he  wants,  including 
binary  fractions;  to  check  up  his  gages  with  other  gages  from  the 
same  set  and  to  do  much  that  has  hitherto  been  possible  only  by 
use  of  measuring  machines  or  micrometers. 

The  smallest  increment  is  small  enough  for  determination  of 
not  only  limits  but  tolerances,  and  the  gages  would  seem  to  furnish 
all  needed  means  for  determining  working  gages  of  any  required 
degree  of  accuracy. 


INDEX 

A 

PAGE 

Accuracy  of  the  lathe  without  special  tools,  testing  the 224 

Adjust  the  needle  of  surface,  how  to 04 

Adjustable  sizing  block ^3 

Adjusting  caliper  gages 22 

snap  gage    208 

try-squares,  method  of  testing 164 

Age  of  interchangeability,  living  in 3 

Aluminum  caliper 29 

American  Machinist    176,  229 

tool-making,  treaties 32 

Ancient  snap  and  plug  gage    3 

Anvil  screws  of  micrometer  with  bastard  threads    24 

Arbor  and  bushing  for  indicating  jig  buttons 36 

Armature  templet,  making  an     125 

Attachment  for  cutting  of  thread  gages 7 

for  the  lathe,  micrometer 217 

for  measuring  instruments 71 

Attachments  for  the  vernier  and  dial  test  indicator 152 

hight  and  vernier  gages  and 152 

Austria'n  work,  gage  practice  in    18 

B 

Ball,  testing  diameter  of 15 

Bar  gages  with  flat  ends,  measuring .- 66 

gages  with  plain  parallel  ends 61 

with  spherical  ends,  sphere 62 

Bates,  Mr.  G.  A 186 

G.  A.,  invention  of 186 

Bath  indicator    71 

Beam  micrometer,  6-inch   200 

Bench  gage,  combination   15 

Bernhard  Fisher   &  Winsch,  Dresden,  Germany n 

Best  manufactured  square 175 

Bevel,  knife-edge 170 

Bored  work,  gaging  the  recess  in 16 

Boring  cutters,  gage  for  testing 99 

master  gage  plates  from  model    38 

235 


236  INDEX 

PAGE 

Boulet,  Beverly,  Mass 215 

Bow-back  gages 72 

British  Westinghouse  works,  large  micrometer  at 203 

Brown  &  Sharpe  Mfg.  Co 111,113 

micrometer 122 

Bullard  Machine  Tool  Co.,  Bridgeport,  Conn 57 

Button  method  of  hole  placing  in  jigs 32 

for  jig  work 35 

C 

Caliper  gages,  adjusting 22 

for  marine  engine  liners,  large  micrometer  part 53 

Cheap  surface  gage   96 

Combination  bench  gage    15 

square  used  as  hight  gage    173 

squares ' 161 

squares,  use  of 172 

Swedish  gages  (Johansson)    230 

Commercial  hardened  squares 161 ' 

Comparison  of  end  standards  of  length  testing  and    61 

Correct  square,  how  to  produce  one    161 

Correcting  squares  when  slightly  out 81 

Cutting  of  thread  gages,  lathe  attachment  for 7 

Cylindrical  gages 15 ,  62 

gages,  measuring 71 

gages,  three-quarter  inch 70 

D 

Decimally  graduated  gage  for  dovetail  slide  inspection 51,  52 

graduated  universal  indicator 90 

Depth  gages    113 

gages,  handy  worm  and  thread 115 

gage,  a  micrometer 122 

Description  of  measuring  machine   62 

Detecting  error  in  index  plates 44 

Development  of  gages i 

Device  for  testing  gages 72 

for  testing  squares    80 

for  testing  up  index  plates    44 

Dial  test  indicator,  attachments  for  the  vernier  and 152 

Diamond-charged  lap,  use  of    5 

powder,  use  for  charging  laps 5 

Different  forms  of  pin  gages    15 

Disk  for  thread  cutting 7 

Dovetail  channel,  gage  for  width  of 50 

slide,  gage  for  testing    51 


INDEX  237 

PAGE 

Dresden  Bohrmaschined  fabrik  A.  G    n 

Drills  and  similar  pieces,  impossible  to  measure  directly 217 

Duplicate  rollers,  test  gage  for  large 54 

work,  inspecting 48 

E 

Electric  measurement  instruments    48 

Emery  for  lapping  gages,  preparation  of 6 

End  standard  of  length,  testing  and  comparison  of    61 

Engine  liners,  large  micrometer  test  caliper  for 53 

English  razor  as  straight-edge 170 

type  of  universal  limit  gage 77 

Equating  micrometer 199 

Essential  necessary  to  the  workman 6 

External  screw  threads  with  the  micrometer,  measuring    197 

F 

Fine  adjustment  of  milling  machine  table in 

Fixture-work,  use  of  gage  in  jig  and 32 

a  rod  gaging   136 

Flat  ends,  measuring  bar  gages  with   66 

square,  simple  method  of  testing 166 

Fly-wheel  segments,  gaging 26 

Form  of  pin  gages,  different    15 

G 

Gages,  adjusting  caliper 22 

bow-back 72 

cheap  surface 96 

combination  bench 15 

cylindrical 62 

depth 113 

determining  proper  relation  of  bevel  gear  faces    83 

development  and  efficiency  of  the  tools    i 

device  for  testing 72 

diameter  of  ball  race  one  crank  shaft  gear   ^ 85 

different  forms  of  pin 15 

dovetail  slide  inspection  51 

end  measurement 56 

fundamentals i 

gaging  systems    i 

gear  tooth 113 

grinding  and  lapping  a  male  plug , 6 

grinding  out  small 5 


238  INDEX 

PAGE 

Gages,  hight,  six-inch ^8 

index  plates,  testing 44 

indicator  for  accurate  index  work,  use  of    40 

indicator  for  thread    I0 

indicator  in  jig  and  fixture  work,  use  of    32 

inside    147 

internal  measuring ^  141 

Johansson    229 

large  duplicate  rollers,  test 54 

large  work,  micrometer 146 

lathe      88 

lathe  attachments  for  thread    7 

locating  keyseats 57 

making 1,4 

making  a  small  micrometer,  inside 141 

manufacturing  mechanisms,  making  and  using  for 12 

measuring  bar  with  flat  ends 66 

measuring  cylindrical     71 

measuring  hair  lines  on  type  faces    78 

measuring  methods  of  Westinghouse  Machine  Co 22 

micrometer 146 

micrometer  adjustment,  universal  surface    in 

micrometer  caliper  for  testing    73 

micrometer  depth   122 

micrometer  heads  for  special    82 

micrometer  hight    193 

millimeter  (25)    69 

millimeter  (150)    69 

miscellaneous 113 

modern  application  of v 3 

new  English  type  of  universal  limit    77 

Newall  working 77 

parallel  vernier    154 

permanent  snap    135 

piston  thread  120 

planer    88,  137 

planer,  a  new  system  of    51 

plates  for  models,  boring  master 38 

plates  for  watches,  making  master    39 

practice i 

practice  at  works  of  Lwdw.  Loewe   &  Co 30 

practice  in  Austrian  iron  works 18 

preparation  of  emery  for  lapping 6 

rebabbitting  journals 83 

remarkable  surface 188 

renewing  of  thread 9 

ring 14. 


INDEX  239 

PAGE 

Gages,  scratching  lines  on  chalked  surfaces 57 

set  of  simple  shop 56 

setting  points  in    8 

slots  in  boring  machine  tables 57 

standard  exact  inch    22 

surface    88 

Swedish    229 

system,  limit    19 

systems,  laid  out 20 

systems,  shops  in  which  they  are  unknown 2 

taper  seats  of  crank  brackets 87 

testing  and  laying  out  fine  work,  hight    156 

testing  centers  on  lathe  work  on  face-plate 101 

testing  cutter  teeth  99 

testing  dovetail  slides 51 

testing  size  and  parellelism  of  holes    17 

testing  truth  of  planing  table   85 

textile  machine  work 138 

thread 113 

thread ,  German    117 

thread  testing    1 1 

three-quarter  cylindrical    70 

tools  for  rolling  sheet  metal    75 

tooth,  a  gear  with  micrometer 215 

type 121 

universal 88 

universal  indicator  and  the  R.  R 109 

universal  indicator,  decimally  graduated    90 

use  on  milling  machine   82 

variation  in  size  of  work  due  to  type  of 18 

vernier  gage  for  testing  snap    154 

wall  thickness,  inspection  of 48 

when  threading,  measuring 8 

width  of  dovetail  channel 50 

work 113 

Gaging  double-head  valves    27 

fixture,  a  rod 136 

fly-wheel  segments 26 

pin  for  bottom  of  holes 15 

small  taper-holes 92 

taper  holes 27 

the  recess  in  bored  work    16 

wheel  joints  for  shrink  fits 27 

Gear  tooth,  gage  for 113 

Geometrical  methods  for  laying  out  right  angles 164 

German  shop  custom  in  gages     1 1 7 

Graduated  disks,  vernier  plate  instead  of 3^ 


240  INDEX 

PAGE 

Graduated  gage  for  dovetail  slide  inspection,  decimally 51,52 

universal  indicator,  decimally    Q0 

Grinding  machine,  indicator  for  setting I08 

straight  work,  gages  for ' ^8 

H 

Hair  lines  on  type  faces,  gage  for  measuring 78 

Handy  thread,  worm,  and  depth  gage 115 

Hardened  cylinder  as  test  block !66 

test  block  with  knife  straight-edge 166 

Hauer,  Charles  E 92 

Heads  for  special  gages,  micrometer    82 

Hight  and  vernier  gages  and  attachments 152 

gage,  a  micrometer 103 

gage  for  testing  and  laying  out  fine  work    156 

gage,  six-inch I58 

gage,  square  used  as    1 73 

gage,  the  R.  R.  universal  indicator  and 109 

gage,  vernier  transformed  into     152 

How  to  make  a  knife-edge  square 167 

to  make  a  large  micrometer 200 

to  produce  a  correct  square  161 

I 

Index  making  another  accurate 44 

plate  making,  use  of  page  and  indicator  in  accurate 40 

plates,  locating  and  swinging 44 

plates,  testing  gage  for  ' 44 

Indicator,  a  lathe x 105 

and  hight  gage,  the  R.  R.  universal  109 

and  holder,  test 102 

and  inclinometer  104 

attached  to  straightening  press 109 

attachments  for  the  vernier  and  dial  test 152 

for  setting  grinding  machine 108 

for  setting  work  in  shaper  or  planer 102 

for  testing  round  pieces 107 

for  testing  up  index  plates 44 

for  thread  gages 10 

lathe  and  planer  92 

sensitive  to  1.200000  part  of  an  inch 106 

test IDT  ,  106 

used  as  a  depth  gage  90 

Indicators,  as  applied  to  milling  machine  99 

for  testing  work,  use  of  test 107 

in  jig  and  fixture  work,  use  of  gage  and 32 


INDEX  241 

PAGE 

Indicators,  in  accurate  index  plate  making,  use  of  gages  and 40 

lathe 88 

planer 1 88 

special    48 

surface   88 

their  construction  and  use    88 

universal    88 

Indicating  gage  for  use  on  milling  machine    32 

Inexpensive  lathe  indicators 88 

Inside  gage    147 

micrometer    143, 145 

micrometer    150 

micrometer  caliper 144, 150 

micrometer  for  4-inch  holes  and  under 149 

micrometer  for  gaging  bored  holes 150 

micrometer  gage  for  making  shrink  fits 145 

micrometers,  outside  and 210 

Inspecting  duplicate  work    48 

Inspection,  gage  for  wall  thickness 48 

gages 48 

graduated  gage  for  dovetail  slide   51 

tools 48 

Instruments,  interchangeability  and  measurements 3 

sensitive  attachments  for  measuring 71 

Instrument  for  internal  hole  measurement    21 

Interchangeability  vs.  measurement  instruments    3 

Internal  hole  measurement,  instrument  for 21 

J 

Jig  and  fixture  work,  use  of  gages  and  fixtures  in    32 

Jigs,  button  method  of  placing  holes  in    32 

Johansson  combination  gages    229 

K 

Kearsarge,  U.  S.  S 54 

Keyseats,  gages  for  locating 57 

Knife-edge  bevel 17° 

squares 161 

squares  with  handle 17° 

straight-edge 17° 

straight-edge i72 

tools,  a  set  of 17° 

L 

Lapping  a  male  plug  gage,  grinding  and    6 

gages,  preparation  of  emery  for 6 

plate  of  vcast  iron I^9 


242  INDEX 

PAGE 

Large  micrometer  caliper  at  the  British  Westinghouse  works 203 

micrometer  test  caliper  for  engine  liners 53 

Lard  oil  used  with  emery 6 

Last  cuts  on  thread  gages 7 

Lathe  and  planer  indicator    92 

attachments  for  cutting  of  thread  gages    7 

bed  templet  for  planing 134 

gages    88 

indicator    105 

indicator,  inexpensive    88 

indicator,  universal    89 

micrometer  attachment  for  the    217 

Laying  out  fine  work,  hight  gage  for  testing  and    156 

Length,  testing  and  comparisons  of  end  standards  of 61 

Limit  gage  practice  at  the  works  of  Ludw.  Loewe   &  Co     30 

gage  system 19 

gage,  English  type  of  .                                            77 

Loewe   &  Co.,  limit  gage  practice  of  work  Ludw 30 

shops,  Berlin,  Germany 30 

Locating  and  swinging  index  plates 44 

keyseats,  gages  for    57 

parts,  making  a  templet  for    130 

work  on  milling  machine,  vernier  method  for     36 

Ludw.  Loewe   &  Co.,  limit  gage  practice  at  works 3o 

M 

Machine,  description  of  measuring 62 

indicators  as  applied  to  milling 99 

material  used  in  measuring   66 

tools,  with  a  micrometer  caliper,  testing.  . 219 

work,  gages  for  textile 138 

Making  a  real  square 175 

a  small  inside  micrometer  gage    141 

a  snap  gage 184 

a  taper  plug  and  ring  gages 4 

a  templet  for  locating  parts 130 

an  armature  templet 125 

and  using  gages  for  manufacturing  mechanism    12 

another  accurate  index  plate 44 

master  gage  plates  for  watches 39 

Male  plug  gage,  grinding  and  lapping 6 

Marbach,  Medina,  Ohio,  Frank  G 210 

Marine  engine  liners,  large  micrometer  caliper  for 53 

Manufacturing  mechanisms,  making  and  using  gages  for 12 

Master  gage  plates  for  models,  boring 38 

gage  plates  for  watches,  making 39 

square,  one  form  of 164 


INDEX 


243 


PAGE 

Materials  used  in  machine 66 

Manchester  works  of  British  Westinghouse  Co 203 

Measuring  bar  gages  with  flat  ends 66 

cylindrical  gages 71 

external  screw  threads  with  the  micrometer 197 

gages  with  threading 8 

hair  lines  on  type  faces 78 

instruments,  sensitive  attachments  for 71 

machine 48 

machine,  description  of 62 

machine,  materials  used  in 66 

methods  at  work  of  Westinghouse  Machine  Co 22 

Measurement  instruments,  interchangeability  and 3 

Method  for  construction  correct  square 163 

for  testing  a  flat  square,  simple   166 

for  testing  try-squares    165 

of  locating  work  on  milling  machine 36 

testing  of  and  adjusting  try-squares    164 

Mechanism,  making  and  using  gages  for  manufacturing 12 

Meter,  micron  the  millionth  part  of 68 

Micrometer  a  6-inch  beam 200 

a  shop  set  of 207 

an  inside  and  outside    210 

attachment  for  the  lathe 217 

beam,  any  mechanic  can  make 200 

Brown  and  Sharpc 122 

caliper,  a  10x12  inch 200 

caliper  at  the  British  Westinghouse  works    203 

caliper  for  measuring  the  radius  of  spindle 217 

caliper  for  testing  gages    73 

caliper,  testing  a  machine  tool  with  a    219 

depth  gage 122 

equating 199 

for  4-inch  hole  under,  inside   149 

for  screw  threads 196 

for  testing  dovetail 49 

gage  for  large  work - 146 

gage  for  making  shrink  fits    145 

gage  on  stand  and  leg 198 

gages,  making  small  inside I41 

gear  tooth  gages 215 

heads  for  special  gages 82 

hight  gage   193 

how  to  make  a  large 200 

inside    141,  i43>  T4S 

measuring  external  screw  thread  with  the 197 

of  English  design *99 


244  INDEX 

PAGE 

Micrometer  outside  196 

practical  shop  use  of 208 

scales 212 

scribing  block 211 

stop 218 

test  caliper  for  marine  engine  liners 53 

testing  a  drill  press  with 200 

testing  a  lathe  of  face-plate  228 

testing  a  machine  vise     221 

testing  hight  and  centers 227 

testing  tail  and  head  centers  with 226 

testing  the  accuracy  of  a  lathe    224 

Micron,  the  millionth  part  of  meter 68 

Miller,  John  C.  Bloomfield,  N.  J 105 

Millimeter  gage  (25) 69 

gage  (150)   69 

Milling  machine,  indicators  as  applied  to   99 

machine  table,  vernier  and  scale  for  fire  adjustment    in 

machine,  use  of  indicating  gage 32 

machine,  vernier  method  of  locating  work  on    36 

Miscellaneous  gages 113 

Models,  boring  master  gage  plates  from  38 

Mott  Street  Factory  of  the  Singer  Company    188 

N 

New  English  type  for  universal  limit  gage 77 

New  system  of  gages  for  the  planer     57 

Newall  working  gages 77 

O 

Outside  and  inside  micrometer 210 

P 

Parallel  ends,  bar  gages  with  plain 61 

testing     46 

vernier  gage 154 

Perfect  square 161 

Permanent  snap  gage    135 

Pin  gages,  different  forms  of 15 

gage  for  bottom  of  hole    15 

Piston-rod,  thread  gage    120 

Plain  parallel  ends,  gages  with 61 

Planer,  a  new  system  of  gages  for  the 57 

gage 137 

gages    88 

indicator,  lathe  and 42 

table  gages  for 85 


INDEX  245 

PAGE 

Planing  a  lathe  bed,  templet  for 134 

Plate  making,  use  of  gages  and  indicator  in  accurate  index 40 

Plates,  testing  gage  for  index 44 

Plug  and  ring  gage,  making  a  taper 4 

gage,  grinding  and  lapping  a  male   6 

gage  usually  made  first   6 

Points  in  gage  setting 8 

Practical  shop  use  of  micrometer 208 

Pratt   &  Whitney 22 

measuring  machine    22 

Precision  square 185 

Preparation  of  emery  for  lapping  gages 6 

Produce  a  correct  square,  how  to 161 

Producing  perfect,  true  try-squares 161 

R 

Real  square,  the  making  of  a    175 

Remarkable  surface  gage   188 

Renewal  of  thread  gages    9 

Reversible  parallel  for  testing  a  square   46 

Ridlon  tools,  Roach  & 109 

Ring  gage,  making  a  taper  plug  and 4 

gages    .  14 

gages,  grinding  out  small   5 

Roach   &  Ridlon  tools    109 

Rod  gaging  fixture 136 

Roll  gage 75 

Rollers,  test  gage  for  large  duplicate 54 

S 

Scale  and  vernier  for  fine  adjustment  of  milling  machine  table in 

Scales,  micrometer ^ 212 

Screw-testing  gage 12 

Screw  threads,  micrometer  for    196 

threads  with  micrometer,  measuring  external 197 

Scribing  block  micrometer 211 

Sensitive  attachments  for  measuring  instruments 71 

Set  of  knife-edge  tools    170 

of  micrometer  calipers,  a  shop 207 

of  simple  shop  gages    56 

Setting  gages,  points  in 8 

Shaw,  P.  E.  of  England 62 

Shop  gages,  set  of  simple 56 

set  of  micrometer  calipers    207 

use  of  micrometers,  practical 208 

Shops  in  which  gaging  system?  ar-  unknown • 2 


246  INDEX 

PAGE 

Simple  and  inexpensive  lathe  indicator 88 

method  for  testing  a  flat  square 166 

Singer  Company,  Mott  Street,  Factory  of 188 

Six-inch  hight  gage    158 

Sizing  blocks,  test  and    161 

block,  adjustable    173 

Slide  inspection,  decimally  graduated  gages  for  dovetail    51 

Slocomb  micrometer  calipers,  set  of  twelve 207 

Slocomb  &  Co.,  J.  T.  of  Providence,  R.  1 82 

Small  inside  micrometer  gages    141 

Snap  gage,  adjustable  208 

gage,  a  permanent 135 

gage,  making  of  a   184 

gage,  vernier  gage  for  testing  in  lapping 154 

Special  gages,  micrometer  heads  for 82 

indicators 48 

Sphere  or  bar  with  spherical  end 62 

Spherical  end  gage 20 

ends,  sphere  or  bar  with 62 

rod  end  gages 18 

Spiral  gear  tooth  gage 113 

Squares,  a  device  for  testing    80 

and  squares 161 

combination 1 61 

commercial  hardened    161 

corrected  when  slightly  out 81 

knife-edge 161 

method  of  testing  and  adjusting  try 164 

perfect    161 

try .v 161 

Square,  a  precision    185 

best  manufactured 175 

gage,  a  remarkable   188 

how  to  make  a  knife-edge 167 

how  to  produce  a  correct 161 

knife-edge  with  handle 170 

making,  templet  for    162 

method  for  constructing  correct 163 

simple  method  for  testing  flat 166 

standard  for  constructing  a  perfect    162 

testing 46 

the  making  of  a  real 175 

used  as  hight  gage 173 

used  in  making  molds    168 

using  test  blocks  in  place  of 165 

Standard  exact  inch  gages 22 

Standards  of  length,  testing  and  comparison  of  end 61 


INDEX  247 

PAGE 

Steel,  question  of 4 

Stop,  a  micrometer    218 

small  defect  in 4 

that  can  be  depended  upon 4 

that  will  not  shrink  or  warp  excessively 4 

to  use  for  gage  work    4 

Straight-edges,  knife-edge    170 

edges 161 

edges,  a  knife-edge 172 

edges,  English  razor  as 170 

edges,  hardened  block  with  knife    166 

Straightening  press  with  indicator  attached    109 

Surface  gage  and  indicator    , 96 

plate,  small  hardened    165 

Surface  gage    88 

gage,  a  cheap 96 

gage,  to  adjust  the  needle  of  a    94 

gage,  with  micrometer  adjustment,  universal    in 

System  limit  gage 19 

of  gages  for  the  planer,  a  new 57 

T 

Taper  gage    121 

plug  and  ring  gage,  making 4 

Tapering  steel  scales 212 

Taps,  gaging  accuracy  of  pitch  of    29 

Templet,  for  locating  parts,  making  a 130 

for  planing  a  lathe  bed 134 

making  an  armature    125 

with  four  sides  for  square  making 162 

Testing  a  comparison  of  end  standards  of  length 61 

accurate  of  pitch  taps 29 

a  flat  square,  easy  method 166 

a  flat  square,  simple  method  for    166 

and  adjusting  try-squares    164 

and  laying  out  fine  work,  hight  gage  for    156 

cutter  teeth 99 

diameter  of  balls 15 

dovetail,  micrometer  for 49 

gage  for  index  plates    44 

gages,  a  device  for    • 72 

gages,  thread    1 1 

machine  tools  with  micrometer  caliper 219 

parallel    '. 46 

screws    12 

size  and  parallelism  of  holes 17 

square 46 


248  INDEX 

PAGE 

Testing  squares,  device  for    80 

the  accuracy  of  a  lathe  without  special  tools 224 

tool  for  fine  work    73 

up  index  plates    44 

work  to  .0001  or  less .  73 

work,  use  of  test  indicator  for    107 

Test  and  sizing  blocks    161 

block,  hardened  cylinder  as 166 

blocks  in  place  of  a  square,  using 165 

caliper  for  marine  engine  liners,  large  micrometer 53 

gage  for  large  duplicate  rollers 54 

gage  for  width  of  dovetail  channel    50 

indicator 101,  106 

indicator  and  hight  gage,  the  R.  R.  universal 109 

indicator  and  holder 102 

indicator,  attachments  for  the  vernier  and  dial 152 

pieces  for  gages 48, 49 

Thread  cutting,  disk  for ' 7 

•    gage,  German 117 

gages,  lathe  attachments  for  cutting  of    7 

gage,  piston-rod 120 

gages 113 

gages,  indicator  for 10 

gages,  renewal  of 9 

leads,  overcoming  variation  in 10 

micrometer  for  screw 196 

testing  gages 1 1 

Thomas,  Mr.  of  Pratt   &  Whitney, 22 

Threading,  measuring  gages  when 8 

Threads  with  micrometer,  measuring  external  screw    .  .  . 197 

Tool-makers  favored  creatures 188 

for  fine  work,  a  testing  for 73 

Try-squares 161 

method  for  adjusting  and  testing 164 

Type  faces,  gage  for  measuring  hair  lines  on 78 

of  gage,  variation  of  work  due  to 18 

of  universal  limit  gage,  a  new  English  type  of    77 

U 

United  States  Watch  Factory,  Marion,  N.  J 189 

Universal  gage •  •  88 

indicator,  decimally  graduated    90 

lathe  indicator    89 

limit  gage,  a  new  English  type  for 77 

surface  gage  with  micrometer  adjustment in 

test  indicator  and  hjght  gage,  the  R.  R 109 


INDEX  249 

PAGE 

Use  of  gages  and  indicators  in  jig  and  fixture  work  32 

of  micrometers  in  accurate  index  plate  making 40 

of  micrometers,  practical  shop , 208 

of  test  indicator  for  testing  work 107 

of  the  combination  square 172 

Using  gages  for  manufacturing  mechanisms,  making  and  12 

test  blocks  in  place  of  a  square 165 

V 

Variation  in  size  of  work  due  to  type  of  gage 18 

in  thread  leads,  overcoming 10 

Verifying  instruments 4 

Vernier  and  dial  test  indicator,  attachments  for 152 

for  fine  adjustment    in 

gage  for  testing  in  lapping  snap  gage    154 

gages  and  attachments,  height  and 152 

gages,  parallel  .  .                              154 

method  of  locating  work  on  milling  machine 36 

plate  instead  of  graduated  disks 36 

transformed  into  a  hight  gage 152 

W 

Wall  thickness,  inspection  gage  for    48 

Watches,  making  master  plates  for    39 

Westinghouse  Electric  Mfg.  Co 92 

Machine  Co 26 

Machine  Co.,  gaging  and  measuring  methods  of 22 

works,  large  micrometers  at  British   203 

Whitworth  plug  and  ring  gage    21 

Wincock,  George   188 

King  of  toolmakers    188 

Work  gages 113 

Works  of  Westinghouse  Machine  Co 22 

Workman,  essential  necessary  to  the 6 

Worm  and  depth  gage,  hand  thread 115 

and  spiral  gear  tooth 113 

and  spiral  gear  tooth  gage  112 


Grinding  ^Lapping 

TOOLS,    PROCESSES    AND     FIXTURES 
By  JOSEPH   V.  WOODWORTH 

Author  of:    "  Dies"  "  Punches,  Dies  and  Tools,"  "  American  Tool-Making 
and  Interchangeable  Parts"  etc. 

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Use  and  Preparation  of  Abrasives. 
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Contain. 


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APR  25  1940 

ADD     2     1&*3 

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YC   19669 


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VVT 


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